"Matching Error" Trying to Add New Book


I’m trying to create a product listing for a new book, but the ISBN is triggering a “matching error”, and it won’t let me add. So I tried a different ISBN. Same thing. And another. Same.

I am self-publishing, and purchased a block of ISBNs from Bowker. The title and ISBNs I am trying to add are not listed on Amazon. I spoke to 2 people from Seller Support today and have not got a resolution yet. Anyone know what a “matching error” is or what triggers it? Or, what can be done about it?