if it had been running fine with the HDR on until recently then it stands to reason it is a driver problem. i see where you say your driver is updated to the latest version, but i dont see where anything has been tried to revert to an older version. i think you should try doing this if you have had HDR running fine before.
first i would start with this older driver since it is very stable.
https://www.guru3d.com/files-details/amd-radeon-adrenalin-edition-18-9-3-driver-download.html
download Display Driver Uninstaller (DDU): https://www.guru3d.com/files-details/display-driver-uninstaller-download.html
then uninstall your current driver, and use DDU to remove remnant files.
after that install the driver you downloaded.
if HDR is working again the good. maybe try updating to a newer version, but not the absolute newest one. see if you can find a driver that works good. its not at all uncommon for bugs to happen or things to get broken in driver releases.
edit:
revisting this thread…
i gave the 19.3.1 drivers a try for a couple weeks to see if they would work out for me. turns out that i got graphical corruption with the drivers.
i reverted back to 18.9.3 and everything is good again.
so yep, as far as my AMD the 19.x.x version drivers are still broken and likely others will find similar bugs though depending on your card manufacturer and your OS your experience may vary.
AMD R9 390 8GB / Windows 7 Pro 64Bit