Any idea why my product is ineligible for a bsr?

This listing has sold over 100 units this month, 50 of those in the last week and seems to be taking off organically because of my competitive pricing, however it still does not show a sales rank even within the inventory manager. My other listing in the same category, nearly identical product received one nearly immediately and has 1/10th as many sales. I emailed amazon support and was told the product is currently ineligible and specific eligibility criteria can not be shared with me.

I should add that this isn’t an adult product, it’s in the pet supplies category.