This issue seems to only occur with RX 5x00 series GPUs and Ryzen 4000 series APUs, which share the same or at least much of the same relatively recent VCN (Video Core Next) 2.0 codec hardware. Older devices appear to be already comprehended in Plex Media Server’s codebase which is why you don’t hear complaints from Ryzen 3000 and 2000 series APU users. I made a GitHub ticket for this issue. Since the RX 5x00 series has been around now for over a year now, it would be nice for support to be fixed for this. See also this related forum thread, where the complaint seems to be coming from only RX 5x00 series GPU and Ryzen 4000 series APU users.
For what it is worth, I just bought a lifetime Plex Pass this week, so I hope that raises awareness among Plex staff that paying customers like myself are looking for dependable support to patch this longstanding issue.
