Inspect the Plex media info XML of these movies.
Look for the first occurence of the XML property addedAt="...
Take the number in there and copy it into the first input field on this website: https://www.epochconverter.com/
Now look at the human-readable date, which is returned by the website.
Is it in the future?
If it is, try the Plex Dance with one of the movies. If that changes the value of addedAt="... to a more sane date, repeat with the rest of the movies.
