We have noticed a successful transaction in payplans that didn't work in PayPal.
It appears that our Payflow account did not have American Express enabled.
When a customer used this payment method PayPal returned this error: code 25 - Transaction not mapped to the host type.
(Your Payflow Pro account isn't set up to process the specified transaction method or card type such as Visa or American Express).
Payplans system should not have accepted the transaction as approved!