I have the exact same problem and I have tried DDU, the AMD cleaning utility, recovering a previous version of windows, reinstalling every version of driver available, manually forcing drivers which then will not start...nothing brings back my HDMI or DisplayPort Audio output. My discrete graphics card is now only good for video as NONE of the outputs provides any audio.
My only remaining idea is to throw away all AMD products and try Intel and Nvidia to see if that works. I am a lifelong computer professional and nothing fixes the problem which leaves me to believe it is the result of a BIOS (UEFI) update from MSI. I cannot test this because MSI claims they would not be providing me with the best computing experience if they allowed me to flash a previous version of the BIOS.
I was cheering for AMD and actually own stock, but this shows they still are not ready for prime time.