AI stop Sensing the player

Hello everyone.
I’ve been struggling figuring out what’s happening with my AI.
I created an AI with 5 states: Nothing, Patrol (which is random location), chase, run away and attack. Basically the AI will walk around, if it sees the player it will run away until the aggro-meter reaches 100%, when it reaches 100 it start chasing the player.
It works perfectly with 1 AI although if I use 2, for some reason, sometimes one of the AI (rarely both) stop “seeing” the player at all! Even when the player is right in front of it. I checked to see if it had anything to do with the NavMesh but both player and AI are on top of the NavMesh. Tried to change the sight radius, lose sight radius and auto success range but seems the problem precists. Can someone tell me what could cause this?
Appreciate!