When stuck in loading hit esc. Should start. If not window out of the game and then back in and hit esc.
As was stated before, this helps in act 2, but not always in act 3. The act 3 issue is rare, though. It stopped happening to me once I installed the Mark of the Assassin DLC, but that's not much of a solution.
December 2014 - last edited December 2014
Using a combination of removing the patch and the continuous escape button mashing that was also mentioned in this thread, which I did right up to the end of the fight I was able to trigger the Leiliana cut scene and complete the quest. So thank you all for your help and suggestions.
Yeah, I hate that this is still an issue. This is a game-breaking bug (especially in Act 3 where the conversation with Sister Nightingale will never trigger.)
I've think i have found a solution..
after the fight you are given some dialog choices.. i picked it like this and it completed the questline..
and it completed..