Under some circumstances, NAS devices can be intolerant of special characters.
I’d try to avoid the é in the file and folder names.
Use Cache (2005) - {imdb-tt0387898}
instead.
Then perform the Plex dance with the file.
Verifying that the file is playing at all (e.g. using VLC) is also a good idea.
Which type of computer are you using to access the NAS?
Is it a Mac?