Happen to me as well, what I found out that makes her move off the screen like that every time is that when you immediately alert 'her' by either pressing space or clicking any task at the start, but not interrupting her when her eye is fully open, she'll begin walking off-screen.
What Archeia probably did is just spam the 'Work' task instead of using the space button to interrupt her, which for some reason breaks the pathing where she moves off-screen instead of to a random task in the room.