FIXED: 4K But No HDR Through Receiver

I'm posting this because it fixed my issue. I found this fix thanks to this community but cannot remember which posts so I'm not trying to pass it off as my brilliance, just want to share in one place.

I have a Yamaha RX-V679 receiver that pushes HDR from my LG UHD blu-ray player just fine, but HDR would not enable on my ATV. I had the correct settings in my TV for deep color, or whatever it is in various brands, no luck.

Turns out with the Yamaha you have to set the 4K signal mode correctly from the receiver, and as much as I hate to say it, cables matter. So....

1 - On the receiver set the correct 4K mode, that can be done by following these (a nice guy named Todd) instructions.

That alone didn't do it.

2 - Then get the right cables. I had nice speedy Amazon Basics that work with everything else but no good, Monoprice is your friend here. I replaced the shorty from my ATV to my AVR, and the long one from the AVR to the TV. Find all lengths here.

Plugged everything in last night and finally, HDR through the receiver. Thanks to those that actually figured this out!