I see all or no products when filtering from the home page in magento

If you have such issue when running Product Parts Finder extension, please create a static block called "Parts Finder" with the content

Then open the store root category, switch to the display options tab, and set display mode "Static block & products",
then select the "Parts Finder" in the static blocks dropdown.  Make sure the category option "Is Anchor" = "Yes"

Save the category.