You can also get the information from Seller University Stranded Inventory Solutions.
Stranded inventory is FBA inventory in fulfillment centers that does not have an associated active offer, and, as a result, is not available for sale on Amazon.
If you have stranded inventory, a Fix Stranded Inventory link appears at the top of the Manage Inventory page. If you do not see this link, you do not have stranded inventory.
Amazon will notify you about stranded inventory in three ways:
If you have stranded inventory, you cannot ship additional units of the product that is stranded to an Amazon fulfillment center. During shipment creation, you will see a stranded inventory alert if you add a product with stranded inventory to your shipment. See below for ways to resolve stranded inventory issues.
When you delete or close a listing, or change it from Fulfilled by Amazon to Fulfilled by Merchant, it may strand your inventory. Product listing issues, infringement concerns, or system errors can also result in stranded inventory.
For the complete list of explanations for stranded inventory, please see Resolve stranded inventory issues.
If there is lost inventory at the fulfillment center, or if there are customer returns of an item, without an active offer, this inventory will be stranded.
If the quantity column is populated on Bulk upload template (eg., Inventory Loader), listings will change from Fulfilled by Amazon to Fulfilled by Merchant automatically which strands your inventory.
Additionally, if you do not fill out the Is this product a battery or does it require batteries? column, it may strand your inventory in some categories.
When you create a new or revise an existing listing, make sure the ASIN, SKU, and condition are the same as the inventory in your stranded inventory list.
Include all vital information for a listing before sending a shipment, including the brand, category, price, and condition.