There's a hella weird glitch in chapter 3, and one of two things triggers this. Either do the falling awning jump in only 3 awnings instead of four (this is possible), or don't use the AC to jump up to the next balcony seconds later. It skips the cutscene and doesn't load the slifing roof sequence, rather nothing in that area properly loads.

I'm coming back to speedrunning UC3, and i can thank jesus christ for that 16 skip