WooCommerce自定义字段未显示在电子邮件或订单信息中

Question

我有customer-id的自定义字段用于客户的订购系统，该字段有效，但由于某些奇怪的原因，它不会发送电子邮件或显示在管理区域的订单信息中。我有来自WooDocs的所有正确代码，但它似乎不起作用，我的代码如下。以下文档的链接。

Customizing checkout fields using actions and filters

/**
* Add the field to the checkout
**/
add_action('woocommerce_before_order_notes', 'my_custom_checkout_field',30);

function my_custom_checkout_field( $checkout ) {

    woocommerce_form_field( 'customer_number', array(
        'type'          => 'text',
        'class'         => array('form-row-wide'),
        'label'         => __('Customer Number <small>(Enter a customer number or leave empty)</small>'),
        'placeholder'   => __('Enter a number'),
        'required'          => false,
    ), $checkout->get_value( 'customer_number' ));
}

add_action( 'woocommerce_checkout_update_order_meta', 'my_custom_checkout_field_update_order_meta' );

function my_custom_checkout_field_update_order_meta( $order_id ) {
    if ( ! empty( $_POST['customer_number'] ) ) {
                        update_post_meta( $order_id, 'Customer Number', sanitize_text_field( $_POST['customer_number'] ) );
    }
}

add_action( 'woocommerce_admin_order_data_after_billing_address', 'my_custom_checkout_field_display_admin_order_meta', 10, 1 );

function my_custom_checkout_field_display_admin_order_meta($order){
    echo '<p><strong>'.__('Customer Number').':</strong> ' . get_post_meta( $order->id, 'Customer Number', true ) . '</p>';
}

add_filter('woocommerce_email_order_meta_keys', 'my_custom_order_meta_keys');

function my_custom_order_meta_keys( $keys ) {
    $keys[] = 'Customer Number'; // This will look for a custom field called 'Customer Number' and add it to emails
    return $keys;
}

提前致谢！