Easiest way to explain would be like this.
SDR - black and white tv
Crappy HDR Tvs - has black, white, red and blue as colors, but most things look black and white
Proper HDR tvs - has all the black to white hues ( all grays ), and all colors
So you have to have a good display to be able to show off HDR. ******/ mediocre tvs will read the format but the image they will show will be limited to the capabilities of said display, in some cases making the image look worse in HDR vs SDR while in others barely better.
@Pottsey your tv is most likely your problem. Either that or you’re the kind of person i was talking about in my previous post who likes his tvs on dynamic contrast vivid colors and everything turned to max and enjoys that black crush/smushed highlights and burnt colors with no hue variation to speak of.