notifications do not display on mac when the app is on a different screen
Macs have the ability to display apps full screen and then switch between those different apps (usually using a 3-finger side-to-side swipe on the touchpad).
If the Teams app is full screen but is not the app that is on the screen then the notifications don't show up. The only way somebody would know that there have been any notifications would be on the badge in the dock, however if you've got the dock hidden (which I do) one might go a long time without seeing the badge.
Please could you make notifications show up regardless of which full screen app is currently visible. thx.
Aaron Dsouza commented
+1 This is very annoying and causes me to miss many notifications
This has got to do with the fact that Teams uses its own notifications system instead of the macOS native notifications.