The Last Imperial & The Sane Cultist
The Last Imperial:
I talked to the imperial then went to destroy the phylacteries, i destroyed all of them but the quest marker still shows that one is not destroyed “Destroy the Phylacteries”.
I went out and back in to do it again, but nothing changed.
The Sane Cultist:
I talked to the cultist went to the ambush and killed the void monsters, i kept going to get out, i talked to the cultist and killed it but the quest still ask to “Confront the “Sane” Cultist in the Ruins of Welryn”.
I went out and back in to do it again, but nothing changed.
Edit: Restarted the game to fix the problem and it worked.