This has happened twice to me so far, resulting in me having to skirt around these parts in quests.
What happens is this: I’m sneaking in a hostile place for a quest and a cutscene triggers. The cutscene plays and ends normally. But when the game loads back in, I am surrounded by almost every hostile in the place! I think that for some reason the hostiles respawn on top of the player as the game loads back in. This happened at Prabizlavytz during the scouting quest, and again at Talmberg in the night raid quest. Fortunately it doesn’t entirely block game progression, but it still stops me from completing the quests in the fashion that I’d prefer.