Best seller ranking not showing

My product is missing its best seller ranking, it used to appear on the product information - additional information section of the listing but that has totally disappeared recently and I can’t work out how to get it back. The only thing I had changed was I had some out of stock product variations attached to the parent (advised by an amazon rep this was ok to do but I realise now I should have closed the listings rather than leave them with 0 stock) i have since made the out of stock products inactive and there are good stock levels on all active products, but my sales have dropped massively and I have no best seller ranking. Case log is useless and no help, any help on here would be really appreciated…Thanks!