Hi,
The issue comes from the products listing which is linked with your filter module.
When you edit the filter module via the Joomla modules manager, you have a menu item id setting where there is the id of a menu item.
This menu item must be of the type "hikashop products listing" and must by default list all the products of your shop.
In your case, that menu doesn't display any product. So when you use the filter module, it filters a products listing which already doesn't contain any products.
So I would recommend to check on that menu item and make sure that you configured it to display all your products.