Quest name: Curious Gorge Meets His Match (level 60 Warrior quest)

This quest requires me to enter a single-player instance, by interacting with the NPC called Broken Mountain, but when I do, the game gives me this error:
"Could not locate data files, please reinstall Final Fantasy XIV.(2ffff)"

And yes, I did reinstall the game, the problem persists. That doesn't happen anywhere else, I can play the rest of the game completely fine.

I'm playing the Steam version of the game.