1. not being able to see him when you don't have your mouse over him is one of the core mechanics of Chapter 4, however he'll also play an audio cue when he's close to you
2. try turning on Reduce Loud Sounds in the audio settings
i know that Chapter 4 has been really hard for some people, if i get a lot of people asking for it i might tone the difficulty down a bit in 2.0
I got some change to ypu model,sorry,also credit to @Emittey