Custom taxonomy display name issue

Your registration is a bit wrong. You did not provide any of the strings necessary to label you taxonomy correctly. Pass an array to `labels’ like this:

register_taxonomy( 
  'location', 
  array( 'post' ), 
  array( 
    'hierarchical' => true, 
    'labels' => array(
        'name'              => _x( 'Genres', 'taxonomy general name' ),
        'singular_name'     => _x( 'Genre', 'taxonomy singular name' ),
        'search_items'      => __( 'Search Genres' ),
        'all_items'         => __( 'All Genres' ),
        'parent_item'       => __( 'Parent Genre' ),
        'parent_item_colon' => __( 'Parent Genre:' ),
        'edit_item'         => __( 'Edit Genre' ),
        'update_item'       => __( 'Update Genre' ),
        'add_new_item'      => __( 'Add New Genre' ),
        'new_item_name'     => __( 'New Genre Name' ),
        'menu_name'         => __( 'Genre' ),
    ), 
    'rewrite' => true 
  ) 
);

I copied that from the Codex so it is for a “Genre” taxonomy, not your “Locations” one but you should see what needs to happen.

Also, pay attention to the keys. There is no singular_label that I can see in the Codex. It is singular_name.