So tonight me and a buddy were working on finishing the devil's voyager commendations, and decided to do a vault in the reach. We've done something like 15 vaults before, but this is only our second ashen. The vault was the Ashen Reaches one.
In the last minute or so of clearing the vault, the island started rumbling. My buddy got out of the vault before it locked and moved the ship out of range of the island, which began erupting, while I looted some gold and took the ferry back to the ship.
The eruption was actually over really quickly - 5 minutes or so - but when we went back, the outer door to the vault had closed, locking our tribute and everything else inside.
Does the outer door in Ashen Reaches close immediately (unlike all of the other vaults we've done, where we can just drop chests outside the inner door and come back after picking up gold until we drown)? Does it close when the island erupts? If we knew, we would have at least grabbed the tribute chest before heading back to the ship; was hard to shake it off and go back to enjoying the rest of the session.
