I have the same problem, after the fight with Raedric, there was no quest update, no cutscene, but I also fought them away from the throne area - made a bottleneck at the nearby door, so maybe that way the bug can be reproduced. I don't know how far back I will have to go to redo this, because I thought nothing was wrong and went back to the city and was expecting to meet Kolsc there and most of my saves are now overwritten. Please fix this, guys, this is kind of game-breaking not to be able to continue the quest chain.