Can't talk to recurring NPC in act 3 sewers

[goodthingsaregood]

I encountered Arabella in a northern cavern of the sewers, and while the 'Talk' interaction appears and my character approaches, nothing happens when they come to talking distance. No other NPC seems to be bugged.

I've tried reloading saves a few hours back, leaving and reentering, restarting, long resting, verifying game files, deleting the level cache data, and even attacking Arabella or hopefully reset her, but nothing has worked.

My best guess is that Arabella triggers a cutscene dialogue connected to her learning to control her powers. But when I read her note in the beginning of act 3, the "Gather Your Allies" quest updated to say she's learned to control her powers and will aid me. So maybe, that bug broke the sewer interaction since that questline had already progressed, even if the NPC hasn't moved.