This guide will help you fixing Windows 10 HDR problems (no HDR on Windows Store Apps like Netflix,no HDR in Games,etc).
This is the file you will get inside the .zip file:
1.Microsoft.HEVCVideoExtension_1.0.31823.0_x86__8wekyb3d8bbwe.Appx
1.Download the .zip file and extract.
2.Double-click on "Microsoft.HEVCVideoExtension_1.0.31823.0_x86__8wekyb3d8bbwe.Appx".
3.Change HDR settings accordingly in Display Settings.
4.Enjoy HDR content!