I don't know if anyone has already pointed this out yet. but if an inmate is still in stocks when you end the day.
They will still have them equipped... It's a minor thing but just something that happens.
It happened to me when I proceed to the next day while I definitely saw one inmate having a stock in their hand and I help then have it in my inventory to this day though I still have it.
The bug is either fixed in the new update or in the github version i can't remember which one
