Monsters may be able to step on special spots
This is an item logged from the To-Do and was originally reported by (@CelticMinstrel?). If you are familiar with this issue, please provide details here.
Special spots refers to the white dots that appear on the terrain marking points of interest (special encounters).
Special spots aren't even drawn in the original game while in battle mode - have we accounted for that? The overworld wandering monsters would still be a problem though.
Wait, what? I don't remember any hiding of special spots in combat mode? I'll have to try that in Basilisk II later… anyway… I'm actually not sure whether this issue was about town monsters or outdoor monsters, so we should probably check both.
Special spots are drawn in combat.
Original Windows BoE:

Well then my memory is incorrect. Still, though, monsters should not activate them. If I was writing the game, I'd check to see if whatever just walked on me is a PC. If that is true (and possibly not being in combat mode, as that could potentially do all manner of strange things), activate it. Otherwise, ignore it.
It's possible you're remembering Exile 2 or 3? I also seem to remember something about special spots disappearing… anyway, in Blades of Exile, special spots are supposed to be treated as impassable by monsters. Probably this was broken when I tore them off the terrain and turned them into a field.