I'm watching Fox and FS1 4K channels through the fuboTV app. Using my new Roku Ultra 2020, the TV detects HDR (HLG), but the picture is obviously SDR. I switched back to my old Roku Premiere, and the picture looks good.
Same problem today. HLG HDR on Fox 4K on fuboTV looks much better on my Roku Premiere compared to my Roku Ultra 2020.