Need Advice: Handling weight discrepancy in Amazon inbound shipment

I have run into a situation regarding inbound shipments to Amazon and could really use some advice. Here’s the bg: We sent a carton weighing 44lbs (this weight is provided by the manufacturer) with a UPS label stating the same weight. However, once Amazon received it, the actual weight might have differed from the stated 44lbs. How and where on SC do we know about this weight discrepancy?

The carton we sent to FBA is missing 50 units. Amazon’s investigation confirmed the shipment contents were short, meaning they never received them and we can no longer seek reimbursement. It’s likely the manufacturer never sent them in the first place.

Now, the manufacturer is saying they need to know the weight of the carton on Amazon’s receiving end. If there’s a weight discrepancy, they will refund us. However, if the weight is the same as they originally specified, then they won’t.

I’m feeling a bit lost on how to navigate this situation. Any advice or insights would be greatly appreciated. Tia!