Microsoft Teams preview in windows 11 showing the message "no core windows message "

I don't know. I know it is still in preview at the time of this post with work still being done on it. At least in Beta Channel. I haven't tested it in Dev Channel. I find Teams better then the other video conferencing brands, but I hardly use it. Maybe wait to the next build to see of that message is still there, and also report that error on Feedback Hub app (found in your Start Menu, under All Apps).