I just had an epiphany! And I fucking hated it.

Room creation events (a.k.a., Room Start) do not get executed until after object creation events. I don't see the logic in that, but that's just how it is. It explains a lot of issues I've been having with Bone Pillars and this recent enemy direction bug.

Lord, give me the strength to not uninstall GameMaker right now. Amen.