There is no specific error that would cause this behavior. In general, a product not showing up on the storefront occurs because some information required for the sale was not filled in or configured correctly.
We have a topic created on this subject, with a series of checks that can be performed for possible causes of this behavior: Dúvidas Frequentes: Produto não aparece no site. O que fazer?
If, even after following all the steps in the topic, the product still isn’t being displayed, we recommend opening a ticket with our support team so that a more thorough investigation can be carried out on a case-by-case basis.