Look at the Plex documentation. There is no dash between movie name and year.
The Plex Movie scanner/agent is more stringent than the legacy agents.
Something else may very well be wrong. However, the first step is using correct naming.
Next step would be to Plex Dance the movie, then pull the server logs.
This will show how Plex is scanning and recognizing the movie. It will also show if there are other problems such as database corruption.
