Was trying to test speedrun KerfurO, pulled the safe out of the water to do the cracking and the door opened by itself (spooky..) but there's nothing inside! Reloaded my safe and kept it in the water when cracking and everything is normal, door opens and AI board inside. Anyone else had the same problem?

I have the same problem 

Had the same problem too and decided to hacksaw it to get metal scrap out of it, but when I did the module appeared along side the scrap.

Had the same issue as well with the same result, amusingly! The door popped open with nothing inside, but when I properly cracked the safe, I opened it again and saw the AI module inside.I feel like the AI module is somehow flagged to spawn inside the safe when it's opened/hacksawed or something.

Indeed, putting the code in spawns the module even if the door is already open. I was pissed for a minute until I read this.

If your safe is already open and there's no O-AI module, hold Use on the front of the safe and put the code in as you normally would, and it should spawn.