Hi,
Sorry for the delay.
I tried to look at the issue again today, but the frontend access you had provided still didn't work bu the admin access allowed me to fix that.
I was able to find the issue. I had to replace the code:
$row = new stdClass();
to:
$row = null;
in the file components/com_hikashop/controllers/order.php in order to fix the issue.
It actually came from the fact that your custom field was limited only to some categories and the system was only taking into account custom fields available for all the categories.
Changing that code avoid the issue.
