Well, I've tried every single suggestion in this thread and not a single one has worked.
A bug as serious as this shouldn't get past QA before the game is shipping, nevermind almost two weeks after it's release. Astounding incompetence.
Don't know if this was said before, I may have looked at this thread myself for answers, but I had this bug and got past it this weekend by:
putting the game in windowed mode (8 attempts and only the 2 in windowed mode worked)
hitting escape to bring up the Skip Cutscene as soon as I could after the boss died and do this for all the cutscenes in between, just choosing whatever responses when that came up
Maybe it will help if it is something you hadn't tried. Being in windowed mode seemed to make the difference, because I did the skipping thing in the usual fullscreen as a trial once and it didn't work then, but the time before and after this worked for me.
