If you use shadowplay it will record HDR in HEVC, it's the only reason I installed shadowplay again. Sadly it seems to have issues now and again where it looses frames, it's the reason I stopped using Shadowplay but there is no other option for HDR. Here is a video I uploaded which also has the frames dropps. Even H.2164 used to do this. OBS and other doftware don't loose frames when recording.
https://youtu.be/8yJpVEM4q-A
Make sure HDR is on in windows and select the 4K 60fps HDR version on the gear icon.