Collision group for zombies to attack(and do damage)

Currently, I am using COLLISION_GROUP_WEAPON for players; but NPCs can not attack them and do damage for some reason.

I’m wondering what a working collision group for players (to no collide to other players) is, without using SetNoCollideWithteammates or a custom collision check (which doesn’t seem to work anyway)

Should I change the collision groups of Zombies or how should I go about this?