Recently, I was doing the Spire of the Watcher solo because i wanted to challenge myself and to get "The Magnificent One" Triumph.
Midway trough, I had to eat but the game kicked me out of the game. "no problem i said, I'll just continue my checkpoint". So I'm at the end, kill Persys, get my loot. I get "One Class Town" & "Three Suns At Noon" Triump and i was telling myself where is the solo triumph. idk if its a bug or I'm stupid but i really don't want to do it again.
Edit: the triumph doesn't say anything without leaving or back to back. Plus i did made my fireteam go on closed, so no one joined.