Did you bring a public version save into a patreon version? Do you remember how you beat the thief? Did you use the ACT skills? This is the only time this has happened or has been reported to me and I can't find any problems with the quests logic in the database, so I wonder what's causing it.
this was back in version 0.66, a few months ago. I meant to ask back than but didnt I just waited for a few updates. how i beat the thief was definitely by "distracting him" using act and taking the bag while hes busy. I can try sharing the save files if that helps. I really dont know what happened. all i remember was turning in the bag, i did the quest twice with no issues third time did it in. i remember examining the bag to see read/open it but pretty sure it didnt let me. ( i consider this a freak accident)
https://drive.google.com/drive/folders/1FPY-3IJA23Xo52bhQDfnVfP5j1n62X-g?usp=dri...
Has it happened in other saves or if you have a newer build, in the new build? 0.66 was a while I go, I wonder if I've fixed that already in the newer builds and just forgot that the quest had a bug.
I think there was something about the quest that I had to look at when the guy who does the preset saves found something. I vaguely remember something like that, but I fixed it back then.
I just did a rerun of the quest and everything worked as they should have, hmmm....
I don't know, since I'm not sure what the thing that causes the problem is. If you can live without that one quest, I think there shouldn't be anything else that could break the save.
I asked permission to download the save file. I can try resetting the quest, but other than that, I don't know how to help.
https://mega.nz/file/DaRRER7L#0Tx75At_YSvnNcHbbt8xRS6cz6MAJFJcOsN7fBpCmYM
This should work. Not sure if it'll break again in 3 tries, but it works now at least.