I tried my Apple TV Plex client and it works fine and it also works on iOS devices fine to. I am running the latest Plex Server on Windows 10 machine Version 1.19.4.2865. I have restarted my plex server app, restarted the machine it is installed on and restarted the Shield TV and nothing is resolving the issue. Something happened with the server or the Plex app on the shield that no longer allows communication to my Plex server DVR service
Server Version#:1.19.4.2865
Player Version#:8.1.0.17967
I am having a very similar issue with my plex server on my shield as it has completely stopped running. Good luck with getting assistance, I’ve been asking for about a month.
Have you tried signing out of your Plex account on your Shield? I just did it on one of mine and signed back in and my 2019 is now working for DVR and Live TV.