I am using MacPro7,1 with an AMD rx6900xt on ASUS Strix Z690 DDR5 . I am also having DRM problem with Amazon Prime app and Safari not working. I am using DisplayPort on version 1.4 to my LG ultra wide. Would be great to know if any of the defaults would help. I might start experimenting the default values based on this page:
Update:
I just tried to enable all these defaults and restarted my desktop, and it didn't seem to make a difference:
defaults write com.apple.AppleGVA gvaForceAMDKE -boolean yes
defaults write com.apple.AppleGVA gvaForceAMDAVCDecode -boolean yes
defaults write com.apple.AppleGVA gvaForceAMDAVCEncode -boolean yes
defaults write com.apple.AppleGVA gvaForceAMDHEVCDecode -boolean yes
defaults write com.apple.AppleGVA disableGVAEncryption -string YES
defaults write com.apple.coremedia hardwareVideoDecoder -string force
Update #2:
I got it to work without any of the defaults above! It is related to my TV connecting to the HDMI port that broke the DRM. I did some experimentation where I have my TV Plugged in then turn on the TV at least once then DRM started working. Interesting enough, I can keep the TV off and DRM continues to work. Without detail testing my guess is after a system restart I probably need to turn the TV on at least once to fix DRM.