AI not performing most actions upon character referencing player controller

I am currently using UE4 for making a simple game to learn the engine. In this game I have created a simple AI that that performs actions such as moving in a nav mesh randomly, can sense the player and follows the player on sight, or when
the player shoots the AI. It’s final, most important task is to shoot the player. Everything was working fine until I implemented a character selection system. This was done by referencing the the player controller through a button on a chac select widget.

The Ai won’t perform most actions now, only occasionally rotating. This is not rotating to face the player, but just random rotations. I have experimented by replacing different nodes and trying many different things, but nothing appears to work.
If someone could review my code and the project file (Which I have linked in two different files) I would be eternally grateful.
Thank you!
Tutorials I used:
Unreal Engine Tutorial - SHOOTING AI! - YouTube

Files:
267163-uehelppics.zip (1.07 MB)
Instrument_wars.zip - Google Drive

It a case such as this, do I copy all the nodes and reference the separate players, or reference the game mode, or controller? (Trombone in this image is one of the characters.) It seems as though the AI just can’t detect a possessed pawn.