Posts uitsluiten van AJAX Search Pro met ACF veld

In functions.php

add_filter('asp_query_args', 'wbmz_exclude_search', 10, 1);
    function wbmz_exclude_search( $args ) {
      $args['post_meta_filter'][] = array(
        'key' => 'niet_indexeren',
        'value' => 1,
        'operator' => '<>',
        'allow_missing' => true
      );
      return $args;
    }