How to display subcategories in main category product list?

[10 Gauge]

I installed a new theme, SNS Nova, and it does not show subcategories in a main category in the product list view, just a message "There are no products in this category".  I have a few main categories that don't have any products in them, they are just to hold subcategories with products.  I want it so that if they click on that main category it will show the subcategories where the products would be displayed instead of the current message (how it works in the default Prestashop theme).  

 

Can anyone help me re-enable this?

 

Thanks!