Plex tries very hard to match movies and often succeeds even though the naming is very wrong but there is no guarantee that future badly named movies will be matched.
The only way to get even close to good consistent matching is to follow Plex’s naming conventions exactly.
You can even add a bit to help Plex. All my movies are named:
MovieName (Year released) (IMDB ID).ext
The MovieName is exactly as it appears in TMdb and the optional IMDB ID is the id for that movie as it appears in the IMDB database.
I found that the few movies I have that consistently mismatched were fixed after I added the IMDB ID.
FileBot is your friend in naming files for Plex. To get the IMDB ID just include {(imdbid)} at the last place in your FileBot movie format string.
One more thing in all the movie agents settings you should more “Local assets” below everything else.
