Microsoft Teams Background options not showing when joining a meeting

This happens to me also.  It drives me crazy, and I have spent way too much time trying to figure out how to fix it!  I have uninstalled/reinstalled, changed my MS 365 subscription, and tried as many things as I can think of.  I set up a custom background when offline, but when I join someone else's meeting, there is no background and no options.  I look pretty lame sitting in front of a green screen.