Well, thank you for your feedback!
There can´t be more than 1 audiolistener in one scene, which is attached to the main player (player 1). Unfortunately I didn´t found a solution for that.. Well, but it is intended that slender is only interacting with the player if he is seen by one of them. Which values did appear on players 2 upper left corner? Did you move the joysticks before the HUD showed up? If not then go to: settings -> controls and then press the button remove deadzone this might help. Yeah.. thats a problem some colliders are inbetween you and slender which will return that slender isn´t seen by the player.
I am glad to hear that you liked the game anyways :) I hope to see you also on my upcomming projects!
Have a awesome day! :)