If my inventory goes missing during fulfilment and the order is not fulfilled, is Amazon supposed to refund me the FBA fee?

I have sparse details of this, but from what I gather, Amazon made a general adjustment and gave a full refund to the customer and one item of my inventory is now being “researched”. I’ve only received general responses from seller support so far, and support telling me that this is NOT a return and there will be no return. So based on the info I have, it seems to be that Amazon lost track of the item during fulfilment.