Still having issues with this setup......
Client says sometimes they pick a show and they get no sound. So she has to go to settings in the atv and restart. This fixes it. She said almost every time she has to do this.
Today, only the apple logo with a grey screen. I power cycled it and everything works. I updated the atv firmware (11.2.6) and now in the middle of updating the Sony 940.
I'm leaving here today with the following settings:
Atv I plugged into input 2 of the Sony 940
HDMI 2 is set for enhanced in the Sony menu

Atv format is set to 4KSDR 60hz
HDMI output is YCbCr
Chroma is 4:2:0
Set to match content (range and frame rate)

From all your experience are these the best settings to have at this point? The one I question is the match content. I'm afraid it may switch a video setting and cause issues. It's not like it's already a pita, but trying to fix this damn thing!!