我有一个名为“参与者”的CPT。当我在仪表板中访问它并搜索属于此CPT的一篇帖子（我搜索的作品是现有帖子标题的一部分）时，WP没有找到任何东西，尽管帖子在列表中，包含我正在搜索的作品。为什么在这种情况下搜索功能不起作用？

以下是我创建CPT的方式：

function my_custom_post_participant() {
    $labels = array(
        \'name\'               => _x( \'Participants\', \'post type general name\' ),
        \'singular_name\'      => _x( \'Participant\', \'post type singular name\' ),
        \'add_new\'            => _x( \'Add New\', \'participant\' ),
        \'add_new_item\'       => __( \'Add New Participant\' ),
        \'edit_item\'          => __( \'Edit Participant\' ),
        \'new_item\'           => __( \'New Participant\' ),
        \'all_items\'          => __( \'All Participants\' ),
        \'view_item\'          => __( \'View Participant\' ),
        \'search_items\'       => __( \'Search Participants\' ),
        \'not_found\'          => __( \'No participants found\' ),
        \'not_found_in_trash\' => __( \'No participants found in the Trash\' ), 
        \'parent_item_colon\'  => \'\',
        \'menu_name\'          => \'Participants\'
    );
    $args = array(
        \'labels\'        => $labels,
        \'description\'   => \'Holds our participants and participant specific data\',
        \'public\'        => true,
        \'menu_position\' => 4,
        \'supports\'      => array( \'title\', \'custom-fields\' ),
        \'has_archive\'   => true,
    );
    register_post_type( \'participant\', $args ); 
}
add_action( \'init\', \'my_custom_post_participant\' );

function my_updated_messages_participant( $messages ) {
    global $post, $post_ID;
    $messages[\'participant\'] = array(
        0 => \'\', 
        1 => sprintf( __(\'Participant updated. <a href="%s">View participant</a>\'), esc_url( get_permalink($post_ID) ) ),
        2 => __(\'Custom field updated.\'),
        3 => __(\'Custom field deleted.\'),
        4 => __(\'Participant updated.\'),
        5 => isset($_GET[\'revision\']) ? sprintf( __(\'Participant restored to revision from %s\'), wp_post_revision_title( (int) $_GET[\'revision\'], false ) ) : false,
        6 => sprintf( __(\'Participant published. <a href="%s">View participant</a>\'), esc_url( get_permalink($post_ID) ) ),
        7 => __(\'Participant saved.\'),
        8 => sprintf( __(\'Participant submitted. <a target="_blank" href="%s">Preview participant</a>\'), esc_url( add_query_arg( \'preview\', \'true\', get_permalink($post_ID) ) ) ),
        9 => sprintf( __(\'Participant scheduled for: <strong>%1$s</strong>. <a target="_blank" href="%2$s">Preview participant</a>\'), date_i18n( __( \'M j, Y @ G:i\' ), strtotime( $post->post_date ) ), esc_url( get_permalink($post_ID) ) ),
        10 => sprintf( __(\'Participant draft updated. <a target="_blank" href="%s">Preview participant</a>\'), esc_url( add_query_arg( \'preview\', \'true\', get_permalink($post_ID) ) ) ),
    );
    return $messages;
}
add_filter( \'post_updated_messages\', \'my_updated_messages_participant\' );

add_filter( \'pre_get_posts\', \'tgm_cpt_search\' );
function tgm_cpt_search( $query ) {
    if ( $query->is_search )
    $query->set( \'post_type\', array( \'page\') );
    return $query;
};