Sorry for the minor thread necro, but don't these screenshots show you using your CPU's transcoder? (Epyc) and not your GTX renderer? sorry-
I came back to this thread after updating to 7.0 and realizing id long forgotten to pass /transcode to /tmp/plex and when reading the thread I noticed this and wondered
To explain away some of your issues here gents (and ladies)
when Plex is in a virgin state or just reset via container you'll need to hit up the port with a /web in your browser.
That's why you're getting the weird XML bug. hit up your.servers.ip.address:32400/web to get around this specific error. if you haven't already resolved this I mean.
Peace