Zolin and zelina bug, i need help

I was completing the game, and in the mission to kill Zolin and Zelina, when I killed them the game bugged. The animation of their death and the loot appeared, but when I talked to the hooded NPC, he didn’t say anything and the mission didn’t complete. When I went back there, Zelina became immortal. I restarted the game and killed them again twice, but it’s still the same. I also let them kill me, but when I came back, the fight didn’t trigger. What could I do?