Small Gray Boxes while Screen Sharing?

Hello!

For my job, I use zoom very often and feel pretty confident in trouble shooting. This morning, however, I encountered a new situation that I can't find any information on or how to fix. While the host is screen sharing, little gray boxes are showing on their screen.. I am familiar with if they have the toolbar or participant list up, there is a large gray box. The host still has nothing on their screen, yet these little gray boxes remain. It shows on each slide in the same place too. 

Has anyone else encountered this?