I had this and think it could do with my media share set to cache=yes. I have set cache=no, run mover and use /mnt/user0/xxxx instead of mnt/user/xxxx in tdarr docker to bypass the cache. Seems to be rock solid now but lots of apps like plex etc. are still writing to cache.   I think I should be able to set my media share back to cache=yes then tdarr should only see the files on the array and pick them up when mover runs... but I've not managed to try it yet