A status about your server being connected solely refers to the server being accessible – this doesn’t say anything about the availability of your files. If files are missing, this should be visible when you open that library or a movie’s details page.
If you cannot see the content of an external drive from within Plex, this is most likely an issue about permissions – this can happen if you’re mounting that drive without considering that Plex is using its own service account on your system. If that service account doesn’t have permission to see your media files, you won’t be able to see them inside Plex.
