Video Card is Radeon RX 470 4GB
PC is connected to Projector by HDMI and used exclusively for TV playback, and recording content through WMC.
All previous driver installs worked ... and continue to do so when reinstalled.
I also have this issue. I have a Radeon R9 390X. For me, it's any version after 19.4.3 that is a problem. I have downgraded back to this version, and everything seems to work.
This is speculation, but it looks like Windows Media Center is not using hardware rendering with the newer drivers. Playback of unprotected content is jerky, with the sound getting out of sync with the video. Protected content playback gives me the HDCP message.
I tried checking for clues between the release notes for versions 19.4.3 and 19.5.2, but there's nothing in the "Known Issues" section specifically or the "Radeon Product Compatibility" that is suggestive of the cause. Checking between 19.1.1 and 19.2.1, similarly yields no clues.
Well, first thing, Window Media Center is not supported by Microsoft after Windows 8.
Neither of you guys mentioned what Windows versions you are running. There is an old workaround to install Windows Media Center in Windows 10 from here: How to Install Windows Media Center on Windows 10 .
It is possible that WMC is now not compatible with the newer drivers. Since WMC is not updated anymore, it can't take advantage of the newer drivers features.
Since Windows 8 is not supported anymore by AMD and Windows 7 will not be supported after January 2020 it is a good possibility you will need to replace WMC with something else.
I replaced WMC with KODI using NPVR as a backend to watch and record TV on my computer.
I am painfully aware of the state of WMC. I thought to give my information on the extremely remote chance that the issue was inadvertent and may have a simple fix. But, I really didn't have much hope for that. It's the end of the road for WMC, but I've definitely got my money's worth.
NextPVR looks nice and seems like a good replacement. I may give that a try. Thanks for the info!
NPVR is an excellent backend but can be used also to watch videos and DVDs and other media. It is a little bit complicated getting it set up to record and download the TV Guide from the internet. But if you go to NPVR Forum you will find out how to program NPVR.
Once you get NPVR set up, install KODI. This is a program very similar to WMC but much better. You can add many Add-ons that enhances the media for the User. Once you install and enabled the NPVR Plugin, everything that you have programmed in NPVR will be seen automatically on KODI. KODI also has a Forum in case you have any problems.