The Fast Velocity Minify plugin has a setting under “HTML Options” to strip HTML comments.

Fast Velocity Minify - strip HTML comments

On all types of listing templates (except ones that use a FacetWP shortcode template) this is problematic, because FacetWP uses <!--fwp-loop--> HTML comments to automatically detect the query results.

So simply turning off this setting should fixes this problem. However, if you want to keep HTML comments stripped out, you also can also add the facetwp-template class to your templates manually. On WooCommerce shop pages, you can use these hooks that do the same.