Error when enabling "Use Alias" in the Payment gateway settings

Hi

If i enable "Use Alias" in the payment gateway settings of the datatrans payment gateway, i receive the following error after i completed a payment:

Drupal\Core\Entity\EntityStorageException: Required payment method field "payment_gateway" is empty. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->save() (line 829 of core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).

While investigating it, it turns out that creating the payment method with this code
$payment_method = $this->createPaymentMethod($post_data);
leads to the error.