The Related Products module is designed for the Product and Category pages, where it is possible to find some products on the page so that a block with related items can be placed. It does not work on CMS pages. On the CMS pages, like the home page, there are no items, so it is not possible to determine any related products. Such a CMS page as the Checkout page is an exception since it contains items, and allows the module to find related products based on the checkout items.