e-mail missing in url on guest-tracking page

[Imre]

Hi!

After guest checkout and payment guest is redirected back to the shop from external payment gateway. Guest should be redirected to guest-tracking page and both order_reference and email should be added to url but for some reason email is not added and guest-tracking page shows error to fill both order reference and email before showing the order details. 

The external payment gateway module code is following:

if ($this->context->customer->is_guest) {
                                                        $email = $this->context->customer->email;
                                                        // $this->context->customer->mylogout(); // If guest we clear the cookie for security reason
                                                        Tools::redirect('index.php?controller=guest-tracking&order_reference='.urlencode($order->reference).'&email='.urlencode($email));
                                                } else {
                                                Tools::redirect('index.php?controller=history');

Which to me looks correct - $this->context->customer->email should return the current users e-mail that they have input when doing guest checkout. But for some reason url without email is returned. For example:

<shop_url>/guest-tracking?order_reference=RBGRLGNZU&email=

My Prestashop version is 1.7.8.0. I think in previous Prestashop versions the email was not mandatory and Prestashop showed the guest order details without problems.

Can someone shed some light on this why it does not work for me?

Best Regards,
Imre