Upon reaching the final stage of the boss arena, when the boss had roughly 1/3 of its health remaining, our fireteam encountered a bug. After entering the portal that connects the second floor to the third floor, we became stuck in an indefinite “joining allies” state. Although we managed to defeat the boss, we were immediately teleported back to the second floor, where the portal to the third floor was now closed. This unfortunately left us in a softlocked state where we could no longer progress the mission.