When the refund button is still showing the cause is that not all parts of the transaction have been refunded yet. You will want to double check if you can reprocess to refund any sub-payments that have not been refunded at this point.
One the sub-payments are refunded the refund button will no longer show. A sub-payment means when your customer has been refunded and money is owed to you from an affiliate. In this case the affiliate owes you.
Anytime you see the “partial error” error, this means one or more of the payments you made on a sale cannot be refunded at this time.