There is a bug in version 1.4.00.16567 on MacOS (11.5.1). When you chat while watching a live meeting, the meeting is minimised to a small floating window. After some clicks, the click handler on that small window breaks, so you cannot restore the video to cover the full teams window any more. Clicking on the video just does nothing.
The only options you have then is to make the live event window full screen or minimized to a small window. This should be fixed.
