ZDoom

Precisely that. The standard case needs special treatment because it cannot be replicated with the other parameters.
Which somehow should have been evident since the defaults for the states are definitely not "Melee" and "Missile" but mere placeholders.

I think because you're keeping the melee and missile states parameters as defaults, [url=https://github.com/coelckers/gzdoom/blob/g4.2.1/src/playsim/p_enemy.cpp#L2778]the old, "hardocded" A_Chase is used[/url].

class blah:demon{
	states{
	melee:
		SARG EFG 6 A_TroopAttack();
	see:
//		SARG AABBCCDD 4 A_Chase("Melee","Melee",CHF_DONTMOVE);
		SARG AABBCCDD 4 A_Chase(flags:CHF_DONTMOVE);
		loop;
	}
}

[code]class blah:demon{
states{
melee:
SARG EFG 6 A_TroopAttack();
see:
// SARG AABBCCDD 4 A_Chase("Melee","Melee",CHF_DONTMOVE);
SARG AABBCCDD 4 A_Chase(flags:CHF_DONTMOVE);
loop;
}
}[/code]Expected: monster will look for targets in one place.

Actual: monster will wander about.

If I swap out the commented line instead, it will do the expected thing.