Sorry for making you wait that long, even though I was the one asking for help.
Luckily it worked now thanks to your help!

For some reason the cutscene in the hallway upstairs didn't trigger for me before but now that I followed the route it did!
This probably also the reason why everything got bugged for me, because it didn't trigger but I still entered the room where the characters where in.

Thank you so much for the assistance!