I found why this happens. I played the 1.1 version of the game with joiplay and encountered this bug.
Using the joiplay debug, i found that cutscene triggers at the front of the dark castle when the variable "chapters" is equal or greater the 17. Even if after the variable is set to 18, it keeps triggering the event responsible must be set at GREATER OR EQUAL THAN 17 instead of just EQUAL 17.
I hope i was clear and got the numbers right for the variable "chapters".