A recent update causes new movies to show the Director and Studio field values from the MP4 tags to appear in the “Directed by” field of the web interface.
Previously-imported movies don’t have this problem, but telling Plex to refresh the metadata causes the symptom to occur for them.
This happens both for movies with matched metadata (IMDB, TMDB) as well as files that can’t be matched in those databases.
The iOS and Apple TV Plex apps don’t exhibit this problem.
Annoying are those reviews we can’t remove - that are ABOVE any Extras I might have, but Director and (useless) Studio (do Rabbits invent studio info?) seem to be unique.
In Settings → Agents → Movies I have both checkboxes ticked on the Personal Media page, all but OpenSubtitles.org checked on the Plex Movie (legacy) tab, and the Local Media Assets (Movies) and the TMDB boxes checked on The Movie Database tab.
Although I anticipate that you’re going to say something about multiple data sources merging to produce this result, allow me to point out that none of these data sources are claiming that, for example, Keystone Film Company directed any of the Charlie Chaplin movies:
Also am curious which app you are using to add tags to your mp4s. On Mac I’ve only ever used metaZ which I do not think has a Studio field. (I just want to try to reproduce myself)