A good idea I think would be to create a new category File, with sub categories image, document, etc.
I guess this would significantly increase the size of the database file. Something to keep in mind.
Are you using KDE by any chance? I had the same issue on Arch Linux with KDE Plasma (which uses Qt), and they advised it's a Qt bug.
As a workaround, you can install a different desktop environment (one that doesn't use Qt), connect Enpass to the cloud and then go back to your preferred DE.
At the moment when pressing the hotkey when Enpass is locked, nothing happens. Would be great if it prompted for your password and then automatically continued auto-filling.