Warning notices from Capture One should be in top layer

I was editing Fuji GFX 100S RAW files and adjusting them and everything worked fine. I exported files to a folder in an attached drive and then started a new batch of similar files and for some reason, after several hours, the program gave a loud “Click!” whenever I tried to access any function or option.

Only after force-quitting Capture One did I discover a small, likely Mac OS warning, that my request to copy some file couldn’t be done as there was another process currently in progress.

When I dismissed that notice window, I was able to reload the files and co Timur editing normally and make any choices of tools I wished.