SPOILER ALERT but only for the very first part of the DLC Through the Ashes
I entered the stage area in sneak mode (being sneaky felt immersive with cultists barely 20 feet away or so). Then walked around, searched, cleared all the rooms further backstage… alone ! (except the one with cultists of course!) Not easy, but I made it.
I came back and found all the NPCs unhelpful
Something was off …
I went back in sneak mode to the basement, searched, talked to the fellow there, came back…
Suddenly, losing patience I stopped being sneaky, I went again to the basement (third times a charm)… Rekarth (who initially had helped my in the basement scripted scene) appears on the stage and I realize the main story event had not triggered because I stepped over it in sneak mode. So… probably easy to fix.
( By “2 companions”, I mean that the other fellow left the basement after Rekarth as scripted.)