在结帐页面上更改计费字段的顺序

我正在使用WC过滤器来订购帐单字段

筛选器似乎工作正常，但由于未知原因，它会即时恢复为默认顺序。

add_filter("woocommerce_checkout_fields", "custom_order_fields");

function custom_order_fields($fields) {
    $order = array(
        "billing_first_name", 
        "billing_last_name", 
        "billing_country",
        "billing_address_1", 
        "billing_address_2",  
        "billing_state",
        "billing_city",
        "billing_phone",
        "billing_email" 
    );

    foreach($order as $field)
    {
        $ordered_fields[$field] = $fields["billing"][$field];
    }

    $fields["billing"] = $ordered_fields;

    $fields['billing_first_name']['priority'] = 10;
    $fields['billing_last_name']['priority'] = 20;
    $fields['billing_country']['priority'] = 30;
    $fields['billing_address_1']['priority'] = 40;
    $fields['billing_address_2']['priority'] = 50;
    $fields['billing_state']['priority'] = 40;
    $fields['billing_city']['priority'] = 70;
    $fields['billing_phone']['priority'] = 80;
    $fields['billing_email']['priority'] = 90;

    return $fields;
}