For me, when Buckhus said "I don't have anything to talk about" I just went to talk someone who i hadn't talked to and came back to talk to Buckhus again. And its where i got the scene (IDK but thats how i do it😶)
Maybe you have to talk to somebody else first or complete all the others "quests?" Firsr. IDK if they're called quests. And then go to talk to Buckhus again see if that works.
I'm out of options😅. Maybe you haven't bought his goods? Or....restart the game Idk. You could ask the creator but he seems to be permanently unavailable.
