Most likely no configuration is missing. There are ongoing issues with the Plex DVR Guide having incorrect episode (and occasionally season) numbers. Comments in other forum threads suggest the new EPG provider Plex switched too is not providing accurate guide information.
This thread indicates a way to report guide issues. I have submitted several examples as outlined in the thread and never saw any corrections on the episodes submitted.
I found I was having to audit the TV guide so as not to miss new shows. The guide issues were so frequent I ended up switching to another EPG guide provider this past week.
