This issue may happen in two cases:
The product you analyze has never been in Amazon warehouses. Amazon does not have data on the product size and weight – in that case, Amazon cannot calculate fees. If the weight is known and only some dimensions are missing, the FBA fee is still calculated from the weight.
Your Amazon Seller account is fresh and not configured. Agree to Amazon FBA terms. Go to the Fulfillment by Amazon on the "Gear" menu or follow the link: https://sellercentral.amazon.com/fba/register/status
The FBA fees data will be displayed after 15 minutes.

