meta format
$meta_query = array( 'relation' => 'AND', array( 'key' => 'link_this_page_to_a_schedule_listing_type', 'compare' => 'EXISTS', ), );
$meta_query = array( 'relation' => 'AND', array( 'key' => 'link_this_page_to_a_schedule_listing_type', 'compare' => 'EXISTS', ), );