Plex not detecting some new TV shows I added

Plex Media Server Metadata & Adding Files
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2
  1. Ensure that only the folder /media/tv has been added to the Plex TV show library.
  2. if the files are in mp4/m4v format, disable “Prefer local meta tags” in the properties of the library, on the Advanced tab. Then perform the Plex Dance with the Show.

And yes, the folder name is supposed to be “Dexter (2006)” because there are other shows with similar titles: dexter — The Movie Database (TMDB)