Please clarify:
Where do you see “not rated”? On watch.plex.tv, or when you add these shows into your personal Plex server?
And if the latter, which country did you select as Cerification Country in the properties of your TV show library?
I think I have found the culprit.
It is once again the bot of TMDB which adds NR to some shows for no reason.
If you have a user account for TheMovieDB.org, you can fix these errors yourself by removing the wrong NR rating.
I have now removed these ratings for the shows you have listed above, but as always it may take a few days before the changes make it into the Plex database.