Best selling item is in stock but isn't buyable

One of our best selling products is in stock but Amazon thinks we have zero stock and as such the item isn't buyable on the product detail page. We have been the featured offer for over 16 months on this product.

Here's a screenshot of the inventory from SKU Central:

And here is a screenshot of the inventory in Manage Inventory:

According to our ERP, we have 500+ units at FBA so the figure in SKU Central are correct.

I have submitted a support case to Seller Support but it's been 2 days without a response.

@Ezra_Amazon @Winston_Amazon Can you help expedite this please? There's clearly an error on Amazon's part here.

Seller Support case ID is: 10011436252

Thanks