Rogue Exiles on top of Abyss not counting as such

So I've had 3 Rogue Exiles so far to spawn on top of the Abyss. Only 1 of these has actually counted as such and spawned the Lich after killing it.

I don't know if it's bugged sometimes. Maybe the rogue exile spawned on the adjacent pixel instead of the correct one? Maybe make the area that counts the monsters for Abyss bigger so this doesn't happen. Just unnecessary feels bad moment imo.

Also I think happened once that the Abyss spawned the horde of monsters because the rogue exile was the last mob and it doesn't wait for it? This is usually nice so you don't need to kill every last one but make an exception for Rogue exiles, please.

No idea how it actually works, would be nice to know if they just have to die on an active abyss, or if they have to spawn on it, or does it need to be both

Dunno, but when I chucked them in the tree and ran abyss maps out of about 7 overrun maps with an exile in them only 1 became a lich

I came here for this very question and problem...