And here is the .capx I made with the exact same settings, except this time it works! Why?
(The Working version does not have a Custom Movement behavior on the enemy, but if you add one with base settings and don't touch it, which is the same for the one in the non-working one, it still works.)
It's imperative for the non-working capx to work, because I already remade all of the numerous abilities, additional enemies, and so on and I need that version of it to work. I've deleted all of them in the capx for protections sake, and to prove that nothing there was actually affecting this bug.