Rabinna doesn't follow the player after saving and loading

I accepted the quest with delivering Rabinna, and she followed my character just fine until I saved the game and exited, and later loaded it again. From there on, she is stuck in place. This leads to not being able to complete the quest.

(RM-3764 from redmine: created on 2017-02-21 by Robbi Blechdose, , closed on 2017-02-21 by nobody, duplicates #3755 (closed))