fourscoopsplease

hopefully this video shows enough. But you can see player triggering trap (though this one heals currently), but when a monster moves over it does nothing. Not shown in the video is that the player can move over the trap repeatedly and set it off each time.

This is the monster setup. It's the same as player from what I can gather.

Any settings I need to be looking into?

gamingislove

The default setup of Trigger Machines only starts them by the player (since you don't want just anything to start them).
See the component's Starting Objects settings - enable Start By Other to allow the machine to be started by other things than the player. You can further add checks to only start by specific things, e.g. by tag or if they have a CombatantComponent attached (all combatants have them).