Fix legacy customer attribute session query

services/nginx/app/objects/users_o.php

@@ -723,7 +723,7 @@ class users_o extends db
             $user_id = $this->id;
         }
         $userIds = $this->attributeSiblingUserIds((int)$user_id);
-        $sql = "SELECT MIN(id) AS id, MIN(user_id) AS user_id, attribute, MIN(created_at) AS created_at
+        $sql = "SELECT MIN(id) AS id, MIN(user_id) AS user_id, attribute, NULL AS created_at
                 FROM customer_attributes
                 WHERE user_id IN (" . implode(',', $userIds) . ")
                 GROUP BY attribute