Amazon changed the rules on back end keywords , just check the blog below that you have them setup correctly;
On August 2nd, 2018, Amazon announced an update to the search term fields in Amazon Seller Central.
The most important changes are:
The total length of search terms is now limited to 249 bytes (compared to 250 bytes before)
This limit now also includes spaces, hyphens, commas etc.
You can only edit or create product listings when your search terms are within the prescribed length limit