I added an old TV movie to my plex movies section. I tried in the fix match section to input the number from imdb tt0088693 to match the movie and it keeps saying that nothing is found. I wonder if there is a setting not on to allow this search to take place.
This is because what you have there is not a movie, but a mini-series.
It was originally aired in 2 parts.
All the metadata sources for Plex are listing it as a series/“tv show”.
So you will only get a match (and get metadata for it) if you put it into a library of the type “tv shows”. Named and organised like a proper tv show in Plex.