Same here, if I get the original confession before the drow, then no "thank you" scene afterwards and the greetings don't change either.
But my game is very glitchy though, I don't get half of his camp cutscenes. My game is not modded and I don't have any performance problems, runs smoothly. But the quests and cutscenes are terribly bugged for me. Granted, I still run pre-patch 2 game, I didn't want to update because of all the problems that people were having.
