Follow these guidelines to avoid the 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 (e.g., 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.