TV And DVR (broadcast channels)

The EPG is kept in tv.plex.providers.epg.cloud-(hash).db file, if you suspect that it is corrupt it is safe to stop Plex and delete the 3 files that start with tv.plex.providers.epg.cloud*. Restart Plex and refresh the guide.

Posting your zip code would aid in determining if the EPG is missing any channels. Missing channels can be reported by using the directions posted here: Reporting Plex DVR Lineup Inaccuracies.