Only Solution for HDR is roll back Nvidia driver to 411.70 TESTED and WORKS perfect again after clean Driver install. ( on Windows 10 1809 Update )
How ?
Use DDU driver uninstaller in windows safe mode , after uninstall download the Nvidia driver 411.70 from the nvidia site, after install everything should work again... AND DON'T update again to 416.16 ... Nvidia FIX YOUR DRIVERS !