Random bug. Not sure how to reproduce it. But happens from time to time.
e.g. I visited Theresa, gave a silver ring to her and then we walked along the river. She did not want to gossip, so I should only accompany her part of the way. After this another dialogue started, the mill in the background, but the same dialogue as before. When the dialogue ended —> Nevenending loading Screen (my first)
Yeah I think it just happens randomly. I have had this happen at different areas on multiple playthroughs. I think this could be the nature of the beast until they patch it.