Open the Nightshoft vault without the key?

Yeah, so I played a match when I approached nightshift, it was still night = the key has not been taken from bushranger. Approached bushranger w a spirit, gave the spirit to them and got the key, the night turned in to day and I ran off to the vault. Just to see that it was already open and looted?

How the f did anyone open the vault w out the key? Is it a bug?