If you join a Prison of Elders game that is in progress, you are stuck in the airlock until the next round opens or the fireteam dies. The problem is, you can't help if you want to and if you go to orbit and go back in, it will try to reconnect you to your previous game. Thus you can rejoin and wait for the rest of the fireteam to finish while you sit back, then collect the loot. It happens because Variks does not call guardians in to the chamber unless it begins and they are not there, so fixing it is simply teleporting guardians in the arena stuck in the airlock even after the round starts. I have seen a few people do this and it starts getting very annoying with only two available members. I also don't have a screenshot or video, but in this case I shouldn't need it. Don't use this exploit just because you saw it here.