Hit a bug. If you go down the stairs from the obvious trap room after the roof without the Delinquent, your character freezes and can't open the menu or anything. I'm guessing it tried to trigger the cutscene with the Delinquent in it and failed to.
It only happened once, though, every other time I've walked down the stairs it's been fine.
I did this using the 'add Delinquent to the party' spot that opens up after reaching the end of the current content(if that counts as a 'cheat'), cuz it was kinda necessary to get the solo table art sequence unlocked. I guess you can do it without that by backtracking, but it's still that I think a lot of people will do it that way, and potentially run into that bug themselves.
