Thanks for the clarification, good to know I was already doing the Plex Dance correctly. 
" * TV shows which are not existing on TheMovieDB.org, but only on TheTVDB.com will often require you to identify them by including the database ID in the folder name. Peruse the above link for the exact syntax."
I’ll look into this. They are popular shows but perhaps adding the ID will resolve whatever issue is making them vanish. It’s at least a thread I can pull on and a possibe explination as to why these 11 of 460 shows are handled differently.
