Maybe it had already been added but has been mismatched as a different item / merged with another movie.
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Check for the 2nd (merged with another movie) → filter your library for duplicates and check if any of those contains the file from your post (e.g.
> Info) -
Check for the 1st (mismatched as a different item) → sort your library by date added… this should show all recent additions on top so you can check if there’s a movie that doesn’t belong and Plex might have mismatched the file from your post as that
If the checks above are getting out of hand (e.g. if you recently added tons of new movies) you should also be able to do a full Plex Dance (full procedure explained in the linked post).
