My agent settings are Plex Movie with IMDB for cast, RT for ratings, and MDb for plot summary.
For example I've added the movie 'The Eyes of My Mother' but not all info has been added, even though its available from the respective sources. Rating, Content Rating, Studio, and Country are all missing.
Refreshing doesn't add the missing information. It's not just this movie but many movies in my library are missing metadata that Plex should have filled in.