Not working from the start

Dear Folders forum – I run up-to-date Gutenberg WP on my iMac. I installed Folders and paid for the pro version. I can create and name folders on the left when I open my media library, BUT I cannot drag and drop images/files from my media library into any of the folders I created. The file(s) just “drift” back to my library (to the right) and the folders remain empty.

I have gotten NO useful help from the developers despite asking. Can some please help? It seems like I am doing the obvious “drag-and-drop”, but is that not the way?!