We noticed that our corporate logo in the bottom right corner of the Powerpoint slide show screen was being cutoff. Apparently the bottom ~1/2" was not appearing on the attendees screens. We were using Show | <Powerpoint slide show>. We tried following tech support's advice and used Show | Rectangle, but it was difficult to adjust correctly and we ended up showing some of the bottom toolbar. We then tried using Show | Rectangle w/o icons and toolbar, but the toolbar was still there.
Our fix, after plenty of fiddling and guessing, was to set the presenter's taskbar to Auto-hide. Then we went back to using Show | <Poweroing slide show> and all displayed well.
There was a 3/20/20 community question where the left side did not show up entirely, and I'm betting that their taskbar was a vertical left side taskbar.
Anyway, this is just FWIW. Tech support has no idea what is causing this problem as of 10/15/20 and says they have received no calls about it.
I'm pretty sure we tried that when online with tech support, and that's why we moved to the rectangle as a way to kinda fix the problem. But I'm happy to try again and be proven wrong 🙂