New Seller – Ungating

Hi everyone, I am pretty much new seller. I applied to sell a brand that is in Supplement section, but it is gated. In order to ungate, I sent an invoice from my supplier and got denied. Since then, I tried several different invoices, even from Target which usually works, and I get a denial every time. But nobody knows why when I call Amazon Seller Support. I know some brands are restricted to new sellers, but this one was wide open , and that same invoice had been used for other brands that were successfully approved, just this one not. The invoice included everything that it should have – my address, suppliers name, etc. I feel bad, as this was very profitable item to sell, and now I have about 200 units at home just because they are not approving me. Pretty tough start to my Amazon career. Any advice where I should get an invoice or other advice?