[2021] Left Asgard before fishing the "Big Finish" quest, and now it's fully bugged

I left the area to wake up before finishing the boss fight, then I didn't play the game for a month until I got the new GPU and started again recently. I just remembered that Asgard wasn't done and went back but I can't progress the quest. I'm stuck on "bring builder's paint to the tower" part, but nothing happens when I do. I can't talk to the builder, all friendly NPCs are gone, Jotnar in the cave are gone/dead too. I was looking for a solution now and found hundreds of people complaining about this quest, is there any way to fix this?