For some reason, while I'm playing a quest, every once in a while, a flying enemy gets stuck at the top left corner of the screen, doesn't animate, and never moves. I haven't figured out what triggers it, as it seems to happen at random as far as I can tell, and it is quite rare. it happened in the BS 1st quest, and in the classic quest a couple times. (It actually got me stuck in a room in level 3 in the BS 1st quest when a Keese got stuck in a room with shutters, and I had to use the "no walls" cheat to get out.
[846] Flying NMEs Appear at Top Left of Screen
It's all enemies.
If the combo at top left most of screen is walkable, ground enemies can spawn there too and not move. Jumpers and fliers can spawn, regardless of the walkablilty of the combo (walk, non-walk).
In a sideview gravity screen, the enemy can spawn anywhere in the left most screen and not move. That's what I saw, I think.
Tentatively fixed!