Edit: I had forgotten about the new change to codelocks where you need to scroll down to detach the lock! Hope this helps anyone else, so I'll leave this thread up
I built a metal door on a small house (single doorway, 2 windows model with little shelves inside.)
I attached a 3 dial codelock while standing inside the house.
The codelock then "forgot" my initial locking numbers, and after exhausting all possible attempts from 000-999 - I realise I'm stuck inside the building. Just wasted a lot of time thinking I had made a mistake or forgotten my code. :(