Find the answer to your question
1. How can I find out if my active inventory was listed with the InventoryTrackingMethod set to SKU?
To retrieve the InventoryTrackingmethod associated with your active items make a call to GetSellerList. If you have a lot of inventory, you will have to make this call multiple times.
Here is a sample -
<?xml version="1.0" encoding="utf-8"?>
The InventoryTrackingMethod tag in the response will tell you what was sent in when the listing was created.
If you have a few items to verify you can download a list of your active items by making a call to ActiveInventoryReport and then making a call to GetItem. The InventoryTrackingMethod tag in the response will tell you what was sent in when the listing was created.
GetSellerList best practices
2. Can I revise my item to set the InventoryTrackingMethod to SKU if I haven't done so while listing the item?
You cannot add the InventoryTracking method tag once the listing is active. However, you can end the item and relist it and set the InventoryTrackingMethod during relist.