The ‘Cancel Orders’ section has track of all the orders that got canceled due to syncing errors between your Amazon and Shopify stores.

There could be various  reasons for failed cancel orders:
1. Order is partially canceled*

2. Reason is not provided for cancelation

3. Order is paid and shipped

Resolution

To process the cancelation of any orders, kindly proceed with full cancelation from Amazon. Do not initiate a Partial cancelation this is not supported by Shopify.

 * Partial cancellation refers to an order; where there are multiple products but cancelation is processed only for a part of that order. For example, if any order has a product with 2 or more quantities then initiate cancelation for all quantities.