src/Controller/CustomerAppAPI/CustomerController.php

@@ -108,6 +108,11 @@ class CustomerController extends ApiController
             ->setEmail($req->request->get('email', ''))
             ->setConfirmed($this->session->isConfirmed());
 
+        // if customer user isn't set, set it now
+        if ($cust->getCustomerUser() == null) {
+            $cust->setCustomerUser($this->session->getCustomerUser());
+        }
+
         // update mobile phone of customer
         $cust->setPhoneMobile(substr($this->session->getPhoneNumber(), 2));