Do you want to use HDR on Windows 11? Go to System => Display and switch on Use HDR.

What if HDR doesn’t work on Windows?

It doesn’t work if you don’t have an HDR supported monitor or an HDR compatible graphics card on your computer. You also need a compatible cable. Windows 11 just switches off HDR again when it doesn’t work. It would be very handy if Windows would give a reason why it doesn’t work!

In my case the refresh rate was set to high! It was on 60 Hz, but my mini Displayport to HDMI cable only supports 30 Hz on a 3840 x 2160 resolution monitor. Switching back to 30 Hz does the trick and now HDR works again. Also a new cable would help!

UPDATE: I have a new cable which supports 8k and 60 Hz.
I can now watch 60 Hz 59.94 Hz content on 3840×2160. If the Use HDR switch switches back to off again on Windows try to reboot Windows. In my case Windows starts up with HDR turned on and it sets the output from 60 Hz to 59.94 Hz.