diff --git a/client/dive-common/components/EditorMenu.vue b/client/dive-common/components/EditorMenu.vue
index c5a2e22..caa6fe0 100644
--- a/client/dive-common/components/EditorMenu.vue
+++ b/client/dive-common/components/EditorMenu.vue
@@ -316,6 +316,7 @@ export default defineComponent({
     const maskLoadingPercent = computed(() => editorOptions.maskLoadingPercent?.value || 0);
     const tooManyMasks = computed(() => editorOptions.tooManyMasks.value);
     const loadingFrame = computed(() => editorOptions.loadingFrame.value);
+    const maskWarningMessage = computed(() => editorOptions.maskWarningMessage.value);
     const pauseOnLoading = computed({
       get() {
         return editorOptions.pauseOnLoading.value;
@@ -335,6 +336,15 @@ export default defineComponent({
           offsetX: 25,
         };
       }
+      if (maskWarningMessage.value) {
+        return {
+          icon: 'mdi-alert-circle-outline',
+          color: 'warning',
+          value: true,
+          content: undefined,
+          offsetX: 25,
+        };
+      }
       if (loadingFrame.value) {
         return {
           icon: 'mdi-spin mdi-sync',
@@ -382,6 +392,7 @@ export default defineComponent({
       maskIcon,
       updateMaskCacheSeconds,
       loadingFrame,
+      maskWarningMessage,
       buttonOptions,
       menuOptions,
       editWhiteColorScale,
@@ -475,7 +486,7 @@ export default defineComponent({
             v-if="button.tooltip
               && (getUISetting('UIVisibility') === true || getUISetting('UIVisibility')[index])"
           >
-            <template #activator="{ on }">
+            <template #activator="{ on: tooltipOn }">
               <v-badge
                 v-if="button.id === 'Mask'"
                 overlap
@@ -494,14 +505,14 @@ export default defineComponent({
                   offset-y
                   :close-on-content-click="false"
                 >
-                  <template #activator="{ on, attrs }">
+                  <template #activator="{ on: menuOn, attrs }">
                     <v-btn
                       v-if="getUISetting('Masks')"
                       v-bind="attrs"
                       :color="isVisible('Mask') ? 'grey darken-2' : ''"
                       class="mx-1 mode-button"
                       small
-                      v-on="on"
+                      v-on="{ ...tooltipOn, ...menuOn }"
                       @click="button.click"
                     >
                       <v-icon>{{ button.icon }}</v-icon>
@@ -512,6 +523,15 @@ export default defineComponent({
                     outlined
                   >
                     <v-card-text>Segementation Masks</v-card-text>
+                    <v-alert
+                      v-if="maskWarningMessage"
+                      dense
+                      text
+                      type="warning"
+                      class="mb-2"
+                    >
+                      {{ maskWarningMessage }}
+                    </v-alert>
                     <v-progress-linear
                       v-if="maskLoadingPercent && maskLoadingPercent < 100"
                       :value="maskLoadingPercent"
@@ -557,13 +577,19 @@ export default defineComponent({
                 :color="button.active ? 'grey darken-2' : ''"
                 class="mx-1 mode-button"
                 small
-                v-on="on"
+                v-on="tooltipOn"
                 @click="button.click"
               >
                 <v-icon>{{ button.icon }}</v-icon>
               </v-btn>
             </template>
-            <span> {{ button.tooltip }}</span>
+            <span v-if="button.id === 'Mask' && tooManyMasks">
+              Too many masks in the current cache window.
+            </span>
+            <span v-else-if="button.id === 'Mask' && maskWarningMessage">
+              {{ maskWarningMessage }}
+            </span>
+            <span v-else> {{ button.tooltip }}</span>
           </v-tooltip>
           <v-btn
             v-else-if="getUISetting('UIVisibility') === true || getUISetting('UIVisibility')[index]"
diff --git a/client/package.json b/client/package.json
index 9fd1696..64af050 100644
--- a/client/package.json
+++ b/client/package.json
@@ -1,6 +1,6 @@
 {
   "name": "dive-dsa",
-  "version": "1.11.25",
+  "version": "1.11.26",
   "author": {
     "name": "Kitware, Inc.",
     "email": "Bryon.Lewis@kitware.com"
diff --git a/client/src/provides.ts b/client/src/provides.ts
index b1ea8f6..f62c980 100644
--- a/client/src/provides.ts
+++ b/client/src/provides.ts
@@ -393,6 +393,7 @@ function dummyState(): State {
         opacity: ref(0.75),
         triggerAction: ref(null),
         loadingFrame: ref(false),
+        maskWarningMessage: ref(null),
         useRLE: ref(false),
       },
       editorFunctions: {
diff --git a/client/src/use/useMasks.ts b/client/src/use/useMasks.ts
index 97590c9..9aa2239 100644
--- a/client/src/use/useMasks.ts
+++ b/client/src/use/useMasks.ts
@@ -66,6 +66,7 @@ export interface UseMaskInterface {
     pauseOnLoading: Ref<boolean>;
     triggerAction: Ref<null | 'save' | 'delete'>; // Used to communicate with the MaskEditorLayer
     loadingFrame: Ref<string | false>;
+    maskWarningMessage: Ref<string | null>;
     useRLE: Ref<boolean>;
   };
   editorFunctions: {
@@ -169,6 +170,23 @@ export default function useMasks(
   const pauseOnLoading = ref(false);
   const maxBrushSize = ref(50);
   const loadingFrame: Ref<string | false> = ref(false);
+  const maskWarningMessage = ref<string | null>(null);
+
+  function tracksHaveMasksConfigured() {
+    return visibleMaskIds.value.length > 0;
+  }
+
+  function setMaskWarning(message: string) {
+    if (!tracksHaveMasksConfigured()) {
+      return;
+    }
+    maskWarningMessage.value = message;
+    loadingFrame.value = false;
+  }
+
+  function clearMaskWarning() {
+    maskWarningMessage.value = null;
+  }
 
   function setEditorOptions(data: {
     toolEnabled?: MaskEditingTools;
@@ -270,6 +288,11 @@ export default function useMasks(
 
   async function getFolderRLEMasks(folderId: string) {
     rleMasks.value = (await getRLEMaskData(folderId)).data;
+    if (tracksHaveMasksConfigured() && Object.keys(rleMasks.value).length === 0) {
+      setMaskWarning('Mask metadata is enabled, but rlemasks.json is empty or missing data.');
+    } else {
+      clearMaskWarning();
+    }
   }
 
   function initializeMaskData(maskData: { masks: Readonly<MaskItem[]> }) {
@@ -323,6 +346,7 @@ export default function useMasks(
         results.forEach(({ trackId, frameId, mask }) => {
           const key = `${frameId}_${trackId}`;
           rleCache.set(key, mask);
+          clearMaskWarning();
           if (rleCache.size === masks.value.length) {
             const endTime = performance.now();
             if (ENABLE_TIMING_LOGS) {
@@ -463,6 +487,7 @@ export default function useMasks(
           const key = `${frameId}_${trackId}`;
           rleCache.set(key, mask);
           inFlightWorker.delete(key);
+          clearMaskWarning();
           maskLoadingPercent.value = (1 - (inFlightWorker.size / subsetSize)) * 100;
           if (rleCache.size === subsetSize) {
             const endTime = performance.now();
@@ -498,11 +523,13 @@ export default function useMasks(
     // Now calculate how many seconds we can cache without exceeding MAX_TEXTURE_PRELOAD
     let cumulativeMasks = 0;
     let maxSeconds = 0;
+    let exceededTextureLimit = false;
     const sortedFrameIds = Object.keys(frameMaskCountMap).map((f) => Number(f)).sort((a, b) => a - b);
     for (let i = 0; i < sortedFrameIds.length; i += 1) {
       const frameId = sortedFrameIds[i];
       cumulativeMasks += frameMaskCountMap[frameId];
       if (cumulativeMasks > MAX_TEXTURE_PRELOAD) {
+        exceededTextureLimit = true;
         break;
       }
       maxSeconds = (frameId - frame.value) / frameRate.value;
@@ -515,7 +542,8 @@ export default function useMasks(
     if (maskCacheSeconds.value > maskMaxCacheSeconds.value) {
       maskCacheSeconds.value = maskMaxCacheSeconds.value;
     }
-    if (maskCacheSeconds.value <= 0.1) {
+    // Only show "too many masks" when we actually hit the texture preload limit.
+    if (exceededTextureLimit && maskMaxCacheSeconds.value <= 0.1) {
       tooManyMasks.value = true;
     } else {
       tooManyMasks.value = false;
@@ -526,6 +554,7 @@ export default function useMasks(
     const key = frameKey(frameId, trackId);
     const cacheFound = cache.get(key);
     if (cacheFound) {
+      clearMaskWarning();
       return cacheFound;
     }
     if (useRLE.value) {
@@ -534,12 +563,21 @@ export default function useMasks(
         loadingFrame.value = key;
         return undefined;
       }
+      if (!mask) {
+        setMaskWarning(`Missing RLE mask for track ${trackId}, frame ${frameId}. Check rlemasks.json mapping.`);
+      }
     } else {
       const key = frameKey(frameId, trackId);
       if (inFlightRequests.has(key)) {
         loadingFrame.value = key;
         return undefined;
       }
+      const hasMaskFile = masks.value.some((item) => (
+        item.metadata?.trackId === trackId && Number(item.metadata?.frameId) === frameId
+      ));
+      if (!hasMaskFile) {
+        setMaskWarning(`Missing mask file for track ${trackId}, frame ${frameId}.`);
+      }
     }
     return undefined;
   }
@@ -564,6 +602,9 @@ export default function useMasks(
   });
 
   watch(visibleMaskIds, () => {
+    if (!tracksHaveMasksConfigured()) {
+      clearMaskWarning();
+    }
     if (maskModeEnabled.value && typeof frame.value === 'number') {
       preloadWindow(frame.value);
     } else if (visibleMaskIds.value.length > 0) {
@@ -605,9 +646,24 @@ export default function useMasks(
     const key = frameKey(frameId, trackId);
     const cacheFound = rleCache.get(key);
     if (cacheFound) {
+      clearMaskWarning();
       return cacheFound;
     }
-    loadingFrame.value = key;
+    if (inFlightWorker.has(key)) {
+      loadingFrame.value = key;
+      return undefined;
+    }
+    const hasRLEMask = Boolean(rleMasks.value[trackId]?.[frameId]);
+    if (!hasRLEMask) {
+      setMaskWarning(`Missing RLE mask for track ${trackId}, frame ${frameId}. Check rlemasks.json mapping.`);
+      return undefined;
+    }
+    preloadWindow(frame.value);
+    if (inFlightWorker.has(key)) {
+      loadingFrame.value = key;
+    } else {
+      setMaskWarning(`Unable to load RLE mask for track ${trackId}, frame ${frameId}.`);
+    }
     return undefined;
   };
   return {
@@ -629,6 +685,7 @@ export default function useMasks(
       tooManyMasks,
       maxBrushSize,
       loadingFrame,
+      maskWarningMessage,
       useRLE,
       maskLoadingPercent,
       pauseOnLoading,