I entered the fortress:
- picked up the bag on the 2nd floor
- walked to Fera to talk to her (said the minimum possible to Fera then left)
- came back and entered the barracks
- went back out to grab the sword from the rack
- went back in & talked to most people in the barracks
- exited the barracks
- talked to the 3 guards outside the barracks
- then became stuck when I reopened the door to go in the barracks
(At some point, either on the way up to Fera on the way back, I may have talked to one of the guards. I'm not 100% sure. I'd try to replicate but my game has autosaved past the start of the infiltration.)
After opening the door, I was able to open the main menu but not do anything else.
If I opened the menu & closed it, it started showing movement arrows again. If I clicked to move, she didn't move and the arrow went away. But if I pulled the menu out again, the movement arrows then started from the place I had clicked (see screenshot).
Thankfully the bug isn't a big deal. The game plays fine once I quit and reload.