Not receiving payments for self shipped orders

Hello.

We self ship orders, and provide a shipment tracking number that is relevant to us and our systems, but this tracking number cannot be checked an online tracking platform.

Customers are receiving their orders, but on amazon it says order might be lost, and the funds are not available for us to withdraw.

Is there a way customers can confirm to amazon that they have indeed recieved their orders, so the funds are released?

Thanks