See this post:
You might have to Plex Dance the files after making any name changes.
The purpose of this is to remove all cached metadata and xml data for an item that Plex usually keeps. This helps when you want to “start from scratch” for particular item
- move all files for the media item out of the directory your Library is looking at so Plex does not “see” it anymore
- update library ( scan for media items )
- empty trash
- clean bundles
- double check naming schema and move files back
- update library
If the problem persists, check the metadata inside the file via MediaInfo or similar tools. Make sure the Movie Name field also has the year and not just the movie name.
Example:
General
Complete name : N:\....\Movies\Terminator 2_ Judgment Day (1991)\Terminator 2_ Judgment Day (1991).m4v
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (isom/iso2/avc1/mp41)
Duration : 2 h 32 min
Movie name : Terminator 2: Judgment Day (1991)
