Refund gives error

If an order paid with a credit card is Processing, and the payment is either processing or complete, I cannot refund the order. When I press refund, enter the full order value as the refund amount, and TEST as the reason and press Refund £n.nn via Revolut Gateway – credit cards I get a dialog asking Are You Sure. Press OK and after a spinner, I get a dialog saying

Revolut: This amount can’t be refunded for this order. Please check your Revolut Business account.

Going to my Revolut app, there’s no record of any refund.

Keith