I think I have the same problem, except a different setup. Apple TV 4K into a Yamaha RX-V681 AV amp that’s HDCP 2.2 compliant wich is then attached to my LG 55UH850V, which are both HDR10 and Dolby Vision compatible.
I also have HDMI 2.0 cables between all component, so there should be enough bandwidth for HDR, etc. I should mention too that I have set the LG TV to use HDMI ULTRA HD Deep Colour across its three HDMI connections.
when I run the Apple TV 4K’s HDR wizard it fails if connected to the Yamaha. Not had a chance to try it connected Direct to the TV yet.
i had a similar problem with the SkyQ 2TB box. My workaround was to attach SkyQ to the TV and set the HDR to 10bit 4:4:4 and then reconnect it to the Yamaha. It retained the settings but I have no idea if it is actually working correctly.
might be worth a try.
itd be better if Apple provide a detailed technical specification of all the components that must be in place to support HDR properly.
I have an update and a solution that worked with my rig.
after a bit of Googling I found an article that reminded me that my Yamaha AV amp has an “Advanced Menu” that’s only accessible via the device itself from standby mode.
in Advanced Menu there is an an option for 4K Mode, either Mode 1or Mode 2. I was using Mode 2, which was causing the problem. I set it to Mode 1 and this resolved the problem for both my Apple TV 4K and my SkyQ set-top box.
good luck and hope you find a similar setting to resolve your problem.
This worked for me. Thank you. Sad to see it's so buried. Took two days to find the solution.
Problems with new Apple TV 4K HDR doesn’t work
