A:Answer I don't have an Xbox One S, but I found that I wasn't getting HDR with a Samsung UBD-K8500 UHD Blu Ray player.
On 5 October, I called Hisense USA support. They said that the 50H8C supported HDR - through the USB ports. I asked whether they had any information if there were any firmware updates forthcoming that would permit HDR through the HDMI ports, and they said they had no such information. I got a little nasty with the support person, asking how they could possibly sell this as an HDR 4k TV. (Not a lot of USB sources of program material.)
I was sufficiently annoyed that I checked with BB. I'd had the set for 60 days, far outside the return windows. However, they offered me full price credit towards another TV if I exchanged it. That's what I did. Thanks, Best Buy.
I'm curious as to how the online reviews that I read of the 50H8C didn't catch the problem.