Stated simply, if a screen has the "First enemy is the ringleader" flag set, and you kill that enemy, it will kill all the other enemies. That's correct. However, if you then leave and come back, the number of enemies spawned is supposed to be 0, but in fact it is just the number that you didn't manually kill.
Ringleader-killed enemies don't count toward the number of killed enemies
This would be the case with Armos and Phantom Ghinis, because since they flicker when spawned, they always return if placed on the screen via the enemy placement box, regardless of quest rules or screen flags.
I was not aware that the spawn type had an effect on whether it would return or not, that's good to know.
However, what would be the correct procedure when a mixed group (poof and flicker) are on the screen, but the flicker ones are lower in the list than the poof ones?
The decrease of the number of enemies to spawn would cause the flicker ones to "fall out" first, right? I ask because that's the type of screen that I noted this on.
After some further testing, I am only seeing this on a screen with flicker-spawned enemies. The number of enemies to spawn after leaving and coming back = the number of flicker-spawned enemies from this time, regardless of whether they died or not. So, I suppose this should be moved to "not a bug." Still, that flicker thing is weird. 😃