When Amazon is showing your product as ineligible probably one of these reasons might be the cause for it:
1. Product is not winning the Buy Box
If products are not winning the buy box you won’t be able to advertise. If your product is not in the Buy Box we highly recommend focusing on winning the buy box.
2. Products are Out of Stock
For products that aren’t available and are out of stock, it is not possible to have active ads running. We recommend checking regularly on the product inventory and keeping it up-to-date.
One additional Info: Being up-to-date on the products inventory benefits regarding amazon’s ranking factor and therefore as well influences about winning the Buy Box.
3. Your Product Categories are Ineligible
Every product must fall under particular categories to advertise on Amazon. We recommend checking on Amazon’s list to see if your products fulfil the requirements.
In addition, kindly double-check that your products are categorized correctly in the backend of your Seller Central. Items such as adult products and used or refurbished products are not eligible for advertising.
4. Not in the Brand Registry
Users need to be in Amazon’s Brand Registry to be eligible to advertise. Users must first meet a few eligibility requirements before getting their enrollment accepted listed on Amazon’s Brand Registry page. The program helps manufacturers and brand owners keep control over their brands within Amazon.
5. Lacking Shipping Capabilities
You must be able to ship across the country that you are selling in.