Have you tried the BBC iPlayer trial HLG video?
It's available in the app - go to settings (on the left menu) and it's under the beta option
See how that plays. You can send feedback.
I do wonder if this is something around HLG (used by the BBC) vs HDR10 on the TV360, with your TV? Your TV should support both HDR10 and HLG formats.
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I know a bit about Wi-Fi, Telecoms, and TV as I used to do it for a living but I'm not perfect so don't beat me up... If you make things you make mistakes!