Amazon FBM Refund Policy

I’ve recently started selling products through FBM and have seen an increase in customer complaints claiming they never received their order.

In every instance, we provided proper shipping through a carrier and uploaded the tracking ID for the customer. Furthermore, the tracking number shows the item was delivered and includes photo evidence.

As the seller in these “delivered but not received” cases, is it our responsibility per Amazon’s policy to handle the issue, and issue a refund or can we direct the customer to Amazon or the shipping carrier for resolution?