I've had this occur now several times. I have an external drive, and I download some files to my external drive. It seems that after restarting qbittorrent (or rebooting, not sure), qbittorrent reports Missing files as status of those torrents (which have already been completed on my external drive). My drive is always connected, so it's not that the files were not available at qbittorrent start (although it may be delayed due to that economical mode where the disk spins down after inactivity).
The even more annoying thing is that it moves all those files to the downloading folder on my internal HDD, they are still intact but placed in folders with hash names (e.g. 1ca4221). Each torrent gets its own folder like that, and inside are the files from the torrent, intact and fully working. If I do a force recheck for the torrents, the files are then moved back properly to the external drive. The problem is this keeps re-happening.
I am on MacOS.
External drive missing files moving to downloading
Re: External drive missing files moving to downloading

Cheers