Current Versions:
Plex on Nvidia Shield 8.20.0.26605
Plex on FireTV Stick 4k 8.20.1.26670
Plex Server 1.23.3.4707
When using the play next episode function out of a still running playback of the previous one, the playback does not start and just an everyrunning loading wheel shows up.
I face this issue on my Nvidia Shield (2019) Pro and on my Amazon FireTV Stick 4k.
Since I observe this since several months it also not looks like some very version specific issue.