I’m not familiar enough with your platform but if you can do the equivalent from Windows, this will allow you to delete the guide-related db’s and start fresh.
- Stop the Plex Update service (Services.msc)
- Exit Plex from the tray icon
- Move the tv.plex.providers.epg.onconnect-* files **from **the %LocalAppData%\Plex Media Server\Plug-in Support\Databases\ folder **to **the desktop
- Start Plex Update service (Services.msc)
- Open Plex
These steps are from Plex DVR Configuration- Refreshing EPG (0%)—Initializing – reviewing that thread or perusing these search results might provide more ideas along these lines.