I have a very odd problem. Im using a vega 56 and have it hooked up to my Samsung q6fn 4k tv. My tv supports Freesync, and HDR at 120 hz for 1080 p and 1440 p and 60 hz for 4k. YCBCR 422 and 444 show up under pixel format for both 1080 p and 4k, but not under 1440 p. The issue with this is I need YCBCR 422 so I can play games in hdr at 10 bit. If I use rgb full or limited I can only do 8 bit dithered hdr.
I'm able to get 422 at 1440 p with my GeForce 1070, but I purchased a vega 56 so I could have freesync and hdr. I've attached a few screenshots to show what's going on including a CRU screenshot.