That's strange, it's working for us.
Try to change the line:
if(!$app->isAdmin() && $translationHelper->isMulti(true) && (class_exists('JFDatabase')||class_exists('JDatabaseMySQLx'))){
by:
if(!$app->isAdmin() && $translationHelper->isMulti(true) && class_exists('JFalangDatabase')){
$db->setQuery($query);
$this->categories = $db->loadObjectList('','stdClass',false);
}elseif(!$app->isAdmin() && $translationHelper->isMulti(true) && (class_exists('JFDatabase')||class_exists('JDatabaseMySQLx'))){
in the file administrator/components/com_hikashop/types/categorysub.php