Why won’t FBA Shipping sync my inventory quantity?
Why is my inventory not synced?
FBA Shipping has nothing to do with syncing inventory counts – the inventory managed by is just used for order fulfillment to pass the orders to Amazon. However, if you would like to sync product and inventory counts, we do have another app that will do so.
Here is SnapSync in the App store https://apps.shopify.com/simplesync-amazon-fba-sync