Product Authenticity Complaint: Amazon can not tell me what is wrong with the invoices

Hi!

One of our products, technically some pieces of metal, that has been sold for years now, one at a week on average, has received a product authenticity complaint.

Our products are obviously original and have always been. One option is to acknowledge that it is our fault (not clicking that unless held at gunpoint), the other is to submit invoices from our supplier. I collected the invoices – proper ones, the only kind we receive – from our supplier from the last year, blacked out the prices and nothing else, translated one invoice to English (they look the same) and Amazon fails to tell me what their problem still is.

We received your submission but do not have sufficient information to reactivate your listings.
Why did this happen?
You have not sent us sufficient information that we previously requested from you. We requested this information to address the complaints we received about the authenticity of your items. For privacy reasons, we do not provide details about our investigation methods.

I messaged the few buyers that bought the item right before the complaint but got no replies. Who can I possibly turn to?