Could you possibly already have a “Noah by Ray Comfort” movie in your library already? If you have one already, it’s possible that Plex is merging it with an “existing” copy in your library, which is why it would vanish once you fixed this item.
In the future, you can try to place the imdb tag {imdb-tt3507142} in the filename so Plex will automatically match this copy of Noah to the proper title without manual intervention. (As seen in the second box in this section of the “Naming your Movies” Plex article)