Apple TV only displays Dolby Vision in 8-bit
For some reason my Apple TV 4K is only displaying Dolby Vision in 8-bit on my LG C9. Everything else hooked up to the LG plays in 10/12-bit Dolby Vision (i.e. UHD Blu-Rays). If I change to plain HDR, it'll play in 10/12-bit.
Apple TV 4K, tvOS 13