In the past few months of gameplay I had similar blockings. It seems to occur much more frequent than in the past.
Just lately I had something similar in the requisitioned barn in Rivington where I had to talk no Nestor but he was nowhere to be found.
One or two other recent hickups like this have occurred. (I do have mods )
Thing I've learned when the game seems mysteriously stuck like that, is to examine the partymembers portraits and if there is a portrait with the text bubble next to it, click on that one. By selecting this member the situation may unblock. (As it did for me in Rivington)
