Plex playing wrong file for a specific episode

[JuiceWSA]

If there is a Title Field in that MP4 file - I’d remove it, or perform The LMA Hack:

Video File Naming

With LMA in priority, Embedded Titles within MP4/M4V files are preferred - even over a perfect file name. Local Media Assets should - AT ALL TIMES - remain enabled (unless specifically instructed to turn it off). Local Media Assets should be ‘Demoted’, to the bottom of the stack of active agents under ALL tabs in Shows and Movies, but should NOT be disabled. Local Media Assets is needed for many things - it doesn’t need to be given Tip-Top-Priority (as Plex has so hatefully placed it as it’s …

If you’re using the new and improved TV Show Agent - you’ll need advanced support to tell you how to tell Plex to STOP preferring embedded metadata in MP4/M4V files - 'cause I don’t have a clue.