Guys if you can help me with this problem,

I have published my product on amazon.com since 3 weeks ago, has assigned the correct category but for some reason is not reflecting the category in the Amazon.com listing, in the details where it should appear in Best Seller Rank nothing comes out and in tools like Helium10 for my ASIN says that the category is not available

I have contacted several times to amazon seller agent but they only tell me they can not change the category because it is already in the correct one but do not give me the solution to also appear in the Best seller Rank.

I know that at the beginning when the product is being launched it is normal but I have been selling up to 6 units a day for more than three weeks now and the problem persists. Can someone help me?