In my Google Developer Console under \"Order Management\" I have a lot of cancelled order like that:
Order history:
Jan 18 2017 5:13 PM Paym
Maybe this article will help you.
It says:
It usually takes about an hour for your order to start getting prepared for shipment. During this time the order will be listed as Pending on your order history page. If it is listed as Pending, you can cancel. You can also cancel your order if your item is not in stock.