Amazon want Invoices from my supplier, but keep rejecting them

Hi, I am at my wit’s end
Amazon have lost 300 pieces of an 8 pallet load before Christmas and I have raised a Case
I have tried so many times to furnish them with an invoice from my supplier that they will accept.

Despite conforming they still reject them, despite my supplier going over and above to try to get me what I need.

Anyone got any hints of tips, as they are very unforthcoming about what is actually wrong with what I send them, despite complying with all they ask.