It's that simple. I completed the entirety of the DLC, and I have every DLC installed, but even after leaving the area and coming back, and restarting the game, Vatnir won't enter a dialogue window, so he remains unrecruitable (says his generic lines and stays in his hidden room, which I obviously already accessed.) I haven't been able to find another solution online, or maybe I missed something small, but I was hoping someone here could help.