Recently, I've experienced (and it seems many others have too!) an issue with the Plex app on my Android phone. When watching a TV episode, after a few seconds playback is randomly stopped and switches to the "Next episode" countdown screen.
Initially, I had assumed the problem was contained within a specific PMS version however attempts to downgrade did not fix the issue. Other users also pointed out a rather obscure "End of file" error in PMS logs.
My next steps were to look into downgrading the app and as it turns out, that was the right choice. I went ahead to ApkMirror and downloaded the Plex 18.104.22.16855 (240ff498) variant which seems to work so far. I haven't experienced any random playback interruptions.
Unfortunately, since I have only experienced this problem on Android, I'm unsure of whether any solutions exist for other platforms like NVIDIA Shield or TV OSs. Hopefully Plex will do their due diligence and fix this issue which has apparently been ongoing for the last five months!