Hi,
You said that when you had the debug activated, you got " the confirmation of payment from HikaShop,". What is that ? The "payment notification" email sent by Hikashop after the order is confirmed ? Or the "order admin notification" email sent by HikaShop when the order is created ?
Was the order status changed to confirmed ?
Are all the other orders getting confirmed properly ? It was only one order that was cancelled ?
In that case, no need for debug, you won't learn anything regarding that issue from the debug with working payments.
Also, you said you got a payment notification email saying that the order was cancelled. What was the email's content ? Could you provide a screenshot ?
Also, do you notice anything different between that order and others that could differentiate it from all the others (supposing that the other orders were properly confirmed) ?