Paypal integration config boo boo

Hi all,
I have a paypal business account configured for Website Payments Standard.

I am using OpenCart 2.0.2.0, configured to use the "PayPal Payments Standard" payments extension. The extension is configured thus:
* email=payments@mydomain.com (valid email address)
* Transaction Method=sale
* All the order statuses are set to "Cancelled" except:
* Completed Status=Complete
* Pending Status=Pending

When I edit my PayPal Website Preferences, I configure:
autoreturn = http://www.mydomain.com/path/index.php? ... d/callback

(/path is the directory under which open cart is installed).

When I test a purchase, it all seems to work, from the customer's perspective. They check out, they log into paypal, they confirm the transaction, they get a receipt from paypal via email. They even get redirected to the open cart success page.

However that's it.
* the customer cannot see the transaction at all in their purchase history.
* if I log into Paypal as the customer, I see the transaction listed there with a status of "Payment - Unclaimed" and the message "payments@mydomain.com hasn't accepted yet".
* if I log into paypal or open cart admin as the vendor, I see no record of the purchase.

Can anyone please point me in the right direction - what am I missing? All my googling has been fruitless. I'm at the end of my tether here.

Thanks in advance,
Adam.

Hey Adam - did you ever get this fixed? I have a very similar problem. Thanks, Erica