Hi Nick,
1) In order to include the Delivery Date in the email subject which is received by the admin, you will need to include the below code in the functions.php file of the theme which is currently active on your site.
add_filter('woocommerce_email_subject_new_order', 'change_admin_email_subject', 1, 2);
function change_admin_email_subject( $subject, $order ) {
global $woocommerce;
$order_id = $order->get_id();
$field_name = get_option( 'orddd_lite_delivery_date_field_label' );
$subject = sprintf( 'New Website Order (%s), ' . $field_name . ' - %s', $order_id, $_POST['e_deliverydate'] );
return $subject;
}
Please let me know whether the provided information helped you to achieve your requirement on your site.
2) Can you please explain us in detail with examples in which cases the delivery date is not sent through? Also, let me know whether the Delivery Date is not sent only to emails or everywhere else too.
Regards,
Komal Maru