Amazon closed my shipment saying no items were in the shipment

Hi everyone, I sell on Amazon handmade and I sent some of my items to FBA. Back in March I sent a package which was delivered two days later, but it had not checked in for two months. Finally, I received an update saying it’s Closed and there are discrepancies on the content. I checked the shipment and it’s saying 0 for all the items I sent.

I saw that I could have them investigate but I need to send in a packing slip which asks for:

Packing list date Shipment or purchase order ID Product names of the missing items Quantity shipped Manufacturer signature or stamp

I made one with the information asked but now they replied:

“I can confirm that the packing list you have given us is invalid as it is not compliant according to Amazon’s standards. Please refer to the information given below and provide us a packing list where in all the requested information is present in it.”

I’m so confused as to what I’ve missed and what is Amazon’s standards? Anyone have any idea or can share any experience dealing with this issue?