It's been a long while since I've played that part, but from what I remember Isabelle definitely does appear on the outside of the moat at some point. Potentially a bug, though I also know at some point she was in some other place (The dungeon for a bit I think?) I also think later on in the story she gets sent elsewhere, so it's also possible that somehow triggered ahead of schedule, but I'd imagine that would have been reported and fixed pretty quickly if so.I know it is kinda silly to ask now, since game is kinda "dead"; but I am kinda confused with something. I am replaying the game after long time and decided to go the dark path. Now I just finished the attack on the Betans and when I speak to Daniele (hope i write the names correctly), she says that she punished Isabelle with cleaning or picking something around the moot. But when I go outside the castle, there is no sign of her anywhere? Is it bug....or am I missing something?
So yeah, try checking all around the place, especially the dungeon, but if she's not anywhere then potentially a bug that was never addressed.