Losing Zoom Screen when I stop sharing

I teach and ESL course to adults with Saddleback College.  I teach on Zoom on my Mac.

I am constantly losing view of my Zoom participants and Zoom tool bar, usually this happens when I stop sharing a screen.  I still hear the audio in my meeting, but I do not see the participants and tool bar.  Then I must go to my Zoom camera icon, right click, and click "Show in Finder"  so that they reappear.  

This is a constant problem - for some reason it didn't happen in my Monday meeting, but then continued on Tues, Wed., and today Thursday, 9/1.

I appreciate any help!