PMS version?
PMS 1.32.8 has a bug where the agents do not always initialize correctly. When this happens, new media will not be recognized. The workaround is to restart PMS. The bug is fixed in 1.40 (release.notes).
Regarding naming:
Naming & Organizing Your Movie Files
Plex Dance the movie after any renaming / reorganization.
This works on my server:
/movies/The Hunger Games Mockingjay - Part 2 (2015)/The Hunger Games Mockingjay - Part 2 (2015).mkv
You can also add the IMDB/TMDB ID to the folder/file name. That will tell Plex exactly which movie to match.
/movies/The Hunger Games Mockingjay - Part 2 (2015) {imdb-tt1951266}/The Hunger Games Mockingjay - Part 2 (2015) {imdb-tt1951266}.mkv
