In situations like this, one of the main problems we have observed is that the imported products are set to be active but not published for the "Online Store" Sales Channel. Please ensure that you click on "Manage" and publish those products for the "Online Store." You can refer to the images below for guidance.

If the above steps do not resolve your problem, please feel free to send us the Product IDs or Names and the brands from which they were imported. Ideally, include some screenshots, and we will further investigate the issue.