Custom AI detection

So I have a player character and an AI that detects me.
I Filter by actor has TAG (PLAYER) AND IT WORKS. even thought my player character has no AI STIMULI. But I dont like the detect the Whole actor method.

Anyway, I want to make the detection system more focused on 2 key areas of my player character HEAD AND SPINE_03. So I created a simple actor with a TAG that I added to my character as a child actor and attached it to either of those bones. BUT it never detects :(.
So upon further testing I just dropped that actor in to the scene to test detection, And if it filters by TAG it never get detected. But as soon as I dont check the tag It does. What I find confusing is it dont seem to matter if I have AI STIMULI or not!
I just need to be able to detect if the AI can see either the head or chest area of my player character depending on If the AI is in combat mode or not.
Any Ideas.

And why does my AI detect things without the Stimuli? I thought that was needed to be detected.