似乎无法发现我做错了什么。

$args = array( 
    \'post_type\' => \'wr_event\', // my custom post type
    \'posts_per_page\' => -1, // show all posts 
    \'meta_query\' => array(
          array(
             \'key\' => \'event_announced\', // a custom field either "on" or "off"
             \'value\' => \'on\',
             \'compare\'  => \'NOT IN\'
             )
    )
);
$loop = new WP_Query( $args );

想法？我试着为value 并尝试了不同的解决方案compare