I've seen a few posts here about ATV 4K issues with various TV's.
I set it up a few weeks ago and seemed fine. I got a message from the client that they get the Apple menu but when they choose a Netflix program it goes black but the audio works.
Honestly, I don't remember how I set up the ATV and TV for video. I do remember a screen on the ATV menu an option for 4:2:2 or similar. I don't think we changed anything in the Sony menu.
My question is how best set up the ATV AND Sony TV to try to avoid any issues.

Did you connect the Apple TV to HDMI 2 or 3?
Did you switch those HDMI inputs to 'Extended mode'?
4:2:2 / 10bit should be fine if you do that.

I'm having this issue as well with the same TV as well as with a Samsung and an LG. The Samsung and LG OLED both have hdmi switches that are 10.2gb. The Apple tv works fine on 4k/60 but will not pass video through 4k Netflix content nor will Prime load.

The Sony is on hdmi 2 and the enhanced setting on the input was set initially.

I don't know which HDMI input it's on. What is the correct one for this situation?
Is the "extend mode" an option in the Sony or ATV? And what should it be on? not extended or extended? (do you mean extended or enhanced per post above?)
TIA!

just had the exact thing happen Friday. Apple TV update and reboot. netflix started working again.

This is an industry wide issue. Mostly reported on Sony Tv's but always with Apple TV 4K. Posts on Mac forums, reddit, everywhere. In this instance, it's not your cables, is simply an issue with Apple TV. Of course the job I've been troubleshooting it for months is a cord cutter and his only source of TV. I've eliminated the matrix switch and went loan to each Apple TV and the problem still exists. This has made me look like a fool on this job and there is nothing I can do about it. A reboot will fix until a period of inactivity then it happens again. Im done with Apple.

It definitely is happening on multiple Sony's with the Apple TV plugged into hdmi 2 locally. The 4k enhanced input setting is enabled. I can also confirm the issue happens when the Apple TV is going through a 10.2gb switch. There doesn't seem like there is anything we can do at the moment to resolve this.

Set it to 1080p.

I have had all kinds of issues with he AppleTV. Set it to 4k 60 SDR and be done. If they want 4k HDR sell them a Roku and have them use Amazon. 4k HDR through the appleTV is too wonky, and it works and sometimes it does not.

I tried this. Also my other issue is using 4k sdr through a 10.2gb/s switch. Menus work fine you'd expect the content to be fine as well. It used to be before Apple updated to the match content format and yes I have tried both on and off for that setting.

the AppleTV 4K has an incredibly annoying habit of going back to 4K if it reboots.

And Obviously, Netflix wont play in 4K when its set to 1080p.

I'm guessing you haven't played with this Apple TV much?

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!!

Are we using a receiver in the loop here? If not, why not just use the Netflix app in the TV?

the Grey screen with an apple logo makes it sound likes it is indeed a bad appleTV.

LOL, you really want to piss the customer off don't you.

Being serious; it maybe that the customer would have no problem using the app in the TV. But for a lot of people, it is to confusing - no matter how straight forward it seems to us.
With the Sony, you often have to search around to find the freaking app you want to use. It will sometimes jump around on the horizontal scroll bar of apps. And of course the customer has to know which scroll bar to go to as well - again obvious to us but maybe not to someone who doesn't see the app they are looking for immediately. The Sony TV app menu is one of the worse.
At least with Netflix, there is a dedicated command to get to it. Other apps, good luck.
And I'm guessing they paid almost 2x the cost for the Apple TV 4K over the Roku, because they want to use their iTunes and other Apple centric stuff. Not going to happen on the Sony TV apps either.

[edit]: If all the firmware updates do not fix the problem. Might be time to short the ATV out and claim warranty for a new one. Hopefully it is not an issue with the TV... yikes!!!!