Payment on hold but Paypal have the tracking number and item has been delivered

Description

I sold an item through eBay and had it delivered via Royal Mail special delivery. I was provided with a tracking number. This item was high risk (a laptop computer) so a hold was placed on the payment. I uploaded the tracking number to Paypal which then confirmed that payment would clear within 1 day of delivery. It has now been over 24 hours since delivery and the payment is still on hold. When I click on the transaction in Paypal to track the shipment, it links straight to the Royal Mail website But when I enter the same tracking number, the number isn’t recognised. So from Paypal’s point of view it looks as if the item hasn’t yet been delivered but the buyer has confirmed they now have it and I don’t know what to do when the RM tracking number isn’t being accepted.