That's a bug because zone type custom fields were not supposed to be used for product custom fields
Replace the whole function state in the file administrator/components/com_hikashop/views/field/view.html.php by that code:
function state(){
$namekey = JRequest::getCmd('namekey','');
if(!empty($namekey)){
$field_namekey = JRequest::getString('field_namekey', '');
if(empty($field_namekey))
$field_namekey = 'address_state';
$field_id = JRequest::getString('field_id', '');
if(empty($field_id))
$field_id = 'address_state';
$field_type = JRequest::getString('field_type', '');
if(empty($field_type))
$field_type = 'address';
$class = hikashop_get('type.country');
echo $class->displayStateDropDown($namekey, $field_id, $field_namekey, $field_type);
}
exit;
}
and it should work properly.