Permissions.
- Make certain you’re not using the automounter and have an /etc/fstab entry for the mount
- Make certain the mount point directory is 755
- After the mount make certain the “other” permissions allow user ‘plex’ minimally to ‘read/execute’ down the tree to the media.
Give this little shell script a shot.
Be certain to run it as user plex so it can behave as Plex would.