I've encountered this again and again, and it's very frustrating.
Sometimes, when I'm editing metadata via the medata panel, I'll hear a (error?) beep, and the file that I'm editing will disappear from the lister. I have no idea where it goes. I've attempted to search the filename on various drives, but have never located these files. I'm not sure what triggers this, but it could be related to accidentally middle clicking a field (I use middle clicking for editing filenames in the lister and sometimes I do this mistakenly in other places). I'm usually editing pretty quickly, from field to field, and it happens suddenly... and then its too late. I've been trying to be more aware of when it happens, but so far, not sure what the trigger is. But since the file seems to be deleted, it should be somewhat obvious in the code where the error resolution is handled wrongly.
DOpus 12.17