No longer able to add new images of videos to background library

This post, and the title, is a repeat of a post from 2018. 

I use Windows and have the latest Zoom desktop client. I have a customized background which works fine. Approximately a year ago, I added two images as backgrounds with no problem--which I can easily confirm because I can and do use those background images.

However, I cannot now ADD any new background images. When I click the little "plus" button to add an image, nothing happens. I've tried using different browsers (Edge, Chrome, Firefox) and they all behave the same. 

In summary: I can delete background images, and I can change background images, but I cannot add background images. 

Any help/comments/suggestions would be most appreciated.