diff --git a/projects/igniteui-angular/src/lib/data-operations/merge-strategy.ts b/projects/igniteui-angular/src/lib/data-operations/merge-strategy.ts
index a7a4f8c1059..ead74931b45 100644
--- a/projects/igniteui-angular/src/lib/data-operations/merge-strategy.ts
+++ b/projects/igniteui-angular/src/lib/data-operations/merge-strategy.ts
@@ -75,7 +75,7 @@ export class DefaultMergeStrategy implements IGridMergeStrategy {
                 index++;
                 continue;
             }
-            const recToUpdateData = recData ?? { recordRef: grid.isGhostRecord(rec) ? rec.recordRef : rec, cellMergeMeta: new Map<string, IMergeByResult>(), ghostRecord: rec.ghostRecord };
+            const recToUpdateData = recData ?? { recordRef: grid.isGhostRecord(rec) ? rec.recordRef : rec, cellMergeMeta: new Map<string, IMergeByResult>(), ghostRecord: rec.ghostRecord, index: index };
             recToUpdateData.cellMergeMeta.set(field, { rowSpan: 1, childRecords: [] });
             if (prev && comparer.call(this, prev.recordRef, recToUpdateData.recordRef, field, isDate, isTime) && prev.ghostRecord === recToUpdateData.ghostRecord) {
                 const root = prev.cellMergeMeta.get(field)?.root ?? prev;
diff --git a/projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts b/projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts
index de6c031eede..62d70acb164 100644
--- a/projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts
+++ b/projects/igniteui-angular/src/lib/directives/for-of/for_of.directive.ts
@@ -271,8 +271,11 @@ export class IgxForOfDirective<T, U extends T[] = T[]> extends IgxForOfToken<T,U
     protected _differ: IterableDiffer<T> | null = null;
     protected _trackByFn: TrackByFunction<T>;
     protected individualSizeCache: number[] = [];
+    /**
+     * @hidden
+     */
     /** Internal track for scroll top that is being virtualized */
-    protected _virtScrollPosition = 0;
+    public _virtScrollPosition = 0;
     /** If the next onScroll event is triggered due to internal setting of scrollTop */
     protected _bScrollInternal = false;
     // End properties related to virtual height handling
@@ -867,7 +870,7 @@ export class IgxForOfDirective<T, U extends T[] = T[]> extends IgxForOfToken<T,U
                 const maxVirtScrollTop = this._virtSize - containerSize;
                 this._bScrollInternal = true;
                 this._virtScrollPosition = maxVirtScrollTop;
-                this.scrollPosition = maxVirtScrollTop;
+                this.scrollPosition = maxVirtScrollTop / this._virtRatio;
                 return;
             }
             if (this._adjustToIndex) {
@@ -1470,11 +1473,12 @@ export class IgxForOfDirective<T, U extends T[] = T[]> extends IgxForOfToken<T,U
         let currentScroll = this.scrollPosition;
         if (this._virtRatio !== 1) {
             this._calcVirtualScrollPosition(this.scrollPosition);
-            currentScroll = this._virtScrollPosition;
+            scrollOffset = this.fixedUpdateAllElements(this._virtScrollPosition);
+        } else {
+            const scroll = this.scrollComponent.nativeElement;
+            scrollOffset = scroll && this.scrollComponent.size ?
+            currentScroll - this.sizesCache[this.state.startIndex] : 0;
         }
-        const scroll = this.scrollComponent.nativeElement;
-        scrollOffset = scroll && this.scrollComponent.size ?
-        currentScroll - this.sizesCache[this.state.startIndex] : 0;
         const dir = this.igxForScrollOrientation === 'horizontal' ? 'left' : 'top';
         this.dc.instance._viewContainer.element.nativeElement.style[dir] = -(scrollOffset) + 'px';
     }
diff --git a/projects/igniteui-angular/src/lib/grids/grid-base.directive.ts b/projects/igniteui-angular/src/lib/grids/grid-base.directive.ts
index 51b1f77df28..47499d958d3 100644
--- a/projects/igniteui-angular/src/lib/grids/grid-base.directive.ts
+++ b/projects/igniteui-angular/src/lib/grids/grid-base.directive.ts
@@ -3718,7 +3718,7 @@ export abstract class IgxGridBaseDirective implements GridType,
 
     protected getMergeCellOffset(rowData) {
         const index = rowData.dataIndex;
-        let offset = this.verticalScrollContainer.scrollPosition - this.verticalScrollContainer.getScrollForIndex(index);
+        let offset = this.verticalScrollContainer._virtScrollPosition - this.verticalScrollContainer.getScrollForIndex(index);
         if (this.hasPinnedRecords && this.isRowPinningToTop) {
             offset -= this.pinnedRowHeight;
         }
@@ -8251,16 +8251,16 @@ export abstract class IgxGridBaseDirective implements GridType,
         // recalc merged data
         if (this.columnsToMerge.length > 0) {
             const startIndex = this.verticalScrollContainer.state.startIndex;
-            const prevDataView = this.verticalScrollContainer.igxForOf?.slice(0, startIndex);
             const data = [];
-            for (let index = 0; index < startIndex; index++) {
-                const rec = prevDataView[index];
-                if (rec.cellMergeMeta &&
-                    // index + maxRowSpan is within view
-                    startIndex < (index + Math.max(...rec.cellMergeMeta.values().toArray().map(x => x.rowSpan)))) {
-                    const visibleIndex = this.isRowPinningToTop ? index + this.pinnedRecordsCount : index;
-                    data.push({ record: rec, index: visibleIndex, dataIndex: index });
-                }
+            const rec = this.verticalScrollContainer.igxForOf[startIndex];
+            if (rec && rec.cellMergeMeta) {
+                this.columnsToMerge.forEach((col) => {
+                    const root = rec.cellMergeMeta?.get(col.field)?.root;
+                    if (root) {
+                        data.push({ record: root, index: root.index, dataIndex: root.index });
+                    }
+                })
+
             }
             this._mergedDataInView = data;
             this.notifyChanges();
diff --git a/projects/igniteui-angular/src/lib/grids/grid/grid.component.html b/projects/igniteui-angular/src/lib/grids/grid/grid.component.html
index 2c588d04f72..9e96d118d99 100644
--- a/projects/igniteui-angular/src/lib/grids/grid/grid.component.html
+++ b/projects/igniteui-angular/src/lib/grids/grid/grid.component.html
@@ -54,7 +54,7 @@
             [IgxScrollInertiaDirection]="this.verticalScrollContainer.dc.instance.scrollDirection">
                 @for (rowData of mergedDataInView; track rowData.record;) {
                     <igx-grid-row  class="igx-grid__tr--merged-top" [gridID]="id" [index]="rowData.index" [data]="rowData.record.recordRef" [metaData]="rowData.record" [style.top.px]="getMergeCellOffset(rowData)"
-                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:isRecordMerged(rowData):false:rowData.record:pipeTrigger"
+                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:hasCellsToMerge:false:rowData.record:pipeTrigger"
                     [ngStyle]="rowStyles | igxGridRowStyles:rowData.record:rowData.index:pipeTrigger" #row>
                     </igx-grid-row>
                 }
@@ -117,13 +117,13 @@
         </ng-container>
         <ng-template #record_template let-rowIndex="index" let-rowData let-disabledRow="disabled" let-metaData="metaData">
             <igx-grid-row [gridID]="id" [index]="rowIndex" [data]="rowData" [disabled]="disabledRow" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):false:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:false:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger" #row>
             </igx-grid-row>
         </ng-template>
         <ng-template #pinned_record_template let-rowIndex="index" let-rowData let-metaData="metaData">
             <igx-grid-row [gridID]="id" [index]="rowIndex" [data]="rowData" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):false:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:false:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger"#row #pinnedRow>
             </igx-grid-row>
         </ng-template>
diff --git a/projects/igniteui-angular/src/lib/grids/grid/grid.pipes.ts b/projects/igniteui-angular/src/lib/grids/grid/grid.pipes.ts
index b6c2091ff0b..52eda88c7ac 100644
--- a/projects/igniteui-angular/src/lib/grids/grid/grid.pipes.ts
+++ b/projects/igniteui-angular/src/lib/grids/grid/grid.pipes.ts
@@ -131,7 +131,7 @@ export class IgxGridUnmergeActivePipe implements PipeTransform {
         }
         let result = cloneArray(collection) as any;
         uniqueRoots.forEach(x => {
-            const index = result.indexOf(x);
+            const index = x.index;
             const colKeys = [...x.cellMergeMeta.keys()];
             const cols = colsToMerge.filter(col => colKeys.indexOf(col.field) !== -1);
             let res = [];
diff --git a/projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.component.html b/projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.component.html
index dd46674993c..e7683ef7c9b 100644
--- a/projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.component.html
+++ b/projects/igniteui-angular/src/lib/grids/hierarchical-grid/hierarchical-grid.component.html
@@ -37,7 +37,7 @@
             [IgxScrollInertiaDirection]="this.verticalScrollContainer.dc.instance.scrollDirection">
                 @for (rowData of mergedDataInView; track rowData.record;) {
                     <igx-hierarchical-grid-row class="igx-grid__tr--merged-top" [gridID]="id" [index]="rowData.index" [data]="rowData.record.recordRef" [metaData]="rowData.record" [style.top.px]="getMergeCellOffset(rowData)"
-                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:isRecordMerged(rowData.record):false:rowData.record:pipeTrigger"
+                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:hasCellsToMerge:false:rowData.record:pipeTrigger"
                     [ngStyle]="rowStyles | igxGridRowStyles:rowData.record:rowData.index:pipeTrigger" #row>
                     </igx-hierarchical-grid-row>
                 }
@@ -91,14 +91,14 @@
         </ng-template>
         <ng-template #hierarchical_record_template let-rowIndex="index" let-disabledRow="disabled" let-rowData let-metaData="metaData">
             <igx-hierarchical-grid-row [gridID]="id" [index]="rowIndex" [disabled]="disabledRow" [data]="rowData" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):false:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:false:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger" #row>
             </igx-hierarchical-grid-row>
         </ng-template>
 
         <ng-template #pinned_hierarchical_record_template let-rowIndex="index" let-rowData let-metaData="metaData">
             <igx-hierarchical-grid-row [gridID]="id" [index]="rowIndex" [data]="rowData" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):false:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:false:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger" #row #pinnedRow>
             </igx-hierarchical-grid-row>
         </ng-template>
diff --git a/projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid.component.html b/projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid.component.html
index 3f435bdb30e..bc331c85ae6 100644
--- a/projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid.component.html
+++ b/projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid.component.html
@@ -37,7 +37,7 @@
             [IgxScrollInertiaDirection]="this.verticalScrollContainer.dc.instance.scrollDirection">
                 @for (rowData of mergedDataInView; track rowData.record;) {
                     <igx-tree-grid-row class="igx-grid__tr--merged-top" [gridID]="id" [index]="rowData.index" [treeRow]="rowData.record.recordRef" [metaData]="rowData.record" [style.top.px]="getMergeCellOffset(rowData)"
-                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:isRecordMerged(rowData):row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
+                    [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowData.index:hasColumnLayouts:hasCellsToMerge:row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
                     [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowData.index:pipeTrigger" #row>
                 </igx-tree-grid-row>
                 }
@@ -97,13 +97,13 @@
         <ng-container *ngTemplateOutlet="hasPinnedRecords && !isRowPinningToTop ? pinnedRecordsTemplate : null"></ng-container>
         <ng-template #record_template let-rowIndex="index" let-disabledRow="disabled" let-rowData let-metaData="metaData">
             <igx-tree-grid-row [gridID]="id" [index]="rowIndex" [treeRow]="rowData" [disabled]="disabledRow" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger" #row>
             </igx-tree-grid-row>
         </ng-template>
         <ng-template #pinned_record_template let-rowIndex="index" let-rowData let-metaData="metaData">
             <igx-tree-grid-row [gridID]="id" [index]="rowIndex" [treeRow]="rowData" [metaData]="metaData"
-                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:isRecordMerged(metaData):row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
+                [ngClass]="rowClasses | igxGridRowClasses:row:row.inEditMode:row.selected:row.dirty:row.deleted:row.dragging:rowIndex:hasColumnLayouts:hasCellsToMerge:row.treeRow.isFilteredOutParent:rowData:pipeTrigger"
                 [ngStyle]="rowStyles | igxGridRowStyles:rowData:rowIndex:pipeTrigger"#row #pinnedRow>
             </igx-tree-grid-row>
         </ng-template>