I seem to be having a similar issue which has cropped up in the last couple weeks:
that is [Plex Playback Error: This Live TV session has ended] message.
Never experienced it prior. I tried refreshing the guide, to no avail. Tried many other things I thought might help, but still the same.
Following is a similar thread with various attempts to fix, but still same outcome.
Trouble Streaming Certain Channels in Web Player - #107 by Mike-E
Added later: Still testing, but I have noticed that if the buffer is used by backing up a minute or so, that the play can be extended without the stop error occurring.
Good luck!
