I did a sundial run, and right after the boss died, I died due to being flung off the ledge. When it auto revived me it spawned me right outside the sundial dome with the reward selection so I was unable to get them. I started running around to try and find a way into it, and as I started getting closer to the boss room the joining allies text popped up, but once Osiris finished talking and the mission end timer started that went away. So to try and get back into the sundial room I tried dying and it spawned me back into the boss room with no way to get out or grab my rewards.