Okay so I Fast-traveled to the location Black Mountain, and upon reaching it, it was all fine, I went into the big round tent when I suddenly couldn't see "Click A to open trunk", I thought "Huh, that's weird"
After that when I left the tent my character sort of started falling a decimeter into the ground then popping back up again repeatably.
I thought, "well, that's even more weird huh".
So I fast-traveled back to Black Mountain and started bopping up and down again through the ground.
I tried fast-traveling to BM once again at which point the game froze during the loading screen.
I restarted my xbox, loaded my last autosave and got a freeze after 5 seconds.
I'm going to load my save again, see if it works this time.
Anyway, there is some serious bug going on at Black Mountain.

Yeah so I reloaded the autosave once again and this time I completed the quest without any bugs.
Still, might be worth checking into.