Issue #31582: Forbidden legend: quest frozen if one of the Gauldurson brothers turns to ashes once beaten
Hard to reproduce, but I put 2 savegames as attachment for investigating. Quest: Forbidden legend (dunGauldursonQST)
At this point of the quest you have to beat the 3 Gauldurson brothers one after the other, and they are in their "ghost" form from the start. Once you beat one, he respawns close to the room main sarcophagus and his 2 other brothers, behind an invisible collision wall preventing you to deal with them any further. BUT, when beating one of them, if ever he is turned to ashes, then he respawns as an ash pile close to the sarcophagus, completely freezing the quest at the end of the 3 fights, and preventing the quest to go on (explosion annihilating all 3 of them, mage ghost spawning, explosion and giving the restored Gauldur amulet as a reward).
I could reproduce it twice, the 2nd brother (Sigdis/bowman, I think) was "affected" by the issue the 2 times, but that doesn't mean the 2 others are clean. The way he was killed must be the problem, but I can't really determine if it was by magic, critical hit, special effect (I'm wielding dawnstar) or any Serana intervention.
While the quest is frozen I don't think it's faulty. Maybe just preventing the 3 brothers from turning to ashes should be enough (maybe with a specific keyword?). That's why I set the 'Actor' category for this bug.