Just re-added the HDHomeRun Premium TV channels back to HDHomeRun tuners in Plex. Deleted the tuners then added them back so Plex could see the new channels and I could select a EPG guide that matched the channels.
Using a couple of shows from the Premium TV lineup, I did a few test recordings and none of them had any audio, and the video was stuttering during playback. Tried Live TV and still no audio and same stuttering video.
All local channels recorded and played backed fine. Same for Live TV.