NA values in netVisual_bubble data slot

[samyuktha-suresh]

Hello!
I have a merged cellchat object with two conditions - young and middle age,

and I was following the tutorial step "Identify dysfunctional signaling by using differential expression analysis". I noticed that sometimes there was an unlabeled column in the output bubbleplot. This seems to be due to some NA values appearing the in gg1$data column "source.target". Is there any reason for this interaction to be given an NA value. And if so, should this be dropped when plotting the bubbleplot?

Thanks a lot!

Sam