I entered the Palace Residence (as suggested by the quest) and left, no problem. In the same stay in Caer Lem, I entered a second time in the residence and the exit box vanished. I tried short rests, long rests, and reloading an earlier save (earlier save was also in the Palace Residence) - none of that restored the exit box.
0.5.42 Stuck in the Palace Residence
6 months ago