Two ways to possibly fix this is to find a way to cause the enemies to not glitch anymore
Or
When you kill the captain to get the key to spawn in the fortress
(Or make it to where when you kill the boss have the door be unlocked and you have to go to it and open it)
Story behind it: me and my friend rolled up to the island being deserted while being on the boss fight, while fighting we had gotten the boss incredibly low, then randomly the boss glitched into the ground, after a few minutes of lobbing fire bombs and blunderbombs the boss finally died, but to our misfortune the key either had spawned inside of the vault or it spawned inside of the ground where the boss was glitched inside of
