Unique thumbnails not being generated for iTunes TV Shows

My library of TV shows is a mix of media purchased through iTunes (converted to clean .m4v files) and Blu-Ray rips via MakeMKV. I do not compress anything further.

The Blu-Ray rips show unique thumbnails for any given episode, apparently from a scene within the episode itself. I like that. However, the TV shows purchased through iTunes simply show the same cover image for all episodes in a given season. A good example would be Game of Thrones - I have both Blu-Ray files and iTunes files since the discs came with HD codes. When named identically, the unique thumbnails only show for only the .mkv version.

I’ve tried converting a few .m4v files to .mkv thinking this was just a file type issue but that did not seem to resolve it, at least on the handful of episodes I tried.

Everything plays fine of course, and Plex correctly identifies everything regardless of the file type as far as I can tell.

An example of the simple file structure I use is below:

TV Shows/Game of Thrones/Season 01/Game of Thrones - S01E01 - Winter is Coming.mkv
TV Shows/Archer/Season 07/Archer - S07E04 - Motherless Child.m4v

Any ideas?

Edit: I should note that I can apparently select a unique image though it does not seem to default to that. Perhaps Plex uses the image tagged to the file itself by iTunes?

Edit Again: Nevermind, I figured it out. Nothing like getting thoughts down in writing before the solution clicks. For the record, I just needed to uncheck “Local Media Assets (TV)” under the agents menu then refresh the library.

You’ll need the LMA agent if you ever want to use a local poster or a sidecar subtitle file.
So instead of deactivating it, just tell Plex to priorise the data from the online services (TheTVDB etc)

Re-activate the LMA agent, but drag its line downwards, so it sits below the line with TheTVDB.

Thanks Otto, that’s probably a better move than outright disabling it, just in case that’s a feature i ever want to use.