When I add 9 files in my project, the top menu and timeline stop working.

When I add 9 files in my new project, timeline and the top menu, which is intended for changing the workspace, stop working. That issue appeared quite unexpectedly, I didn't update PrPro and any Adobe programs, services and plugins. Previous my big project worked without any problems.

I use version 15.2. Check out the bottom video. You can rewind the video to 1:00