How to use get_post_custom_values to return the value of an array

If you change

foreach($tracklist as $track) {
  echo $track . "<br>"; // Displays "12" (there are 12 tracks on this album)
}

to

foreach($tracklist as $key => $value ) {
    echo "$key  => $value ('tracklist')<br />"; // Displays "12" (there are 12 tracks on this album)
}

then what you get?