Storefront theme : Add Categoy to recent products section

I want to modify the Recent Products section Storefront theme to be able to include juste a specific category.
i tried that :

add_filter( 'storefront_recent_products_args', 'my_custom_storefront_category_args' );
function my_custom_storefront_category_args( $args ){
   $args = array(
    'limit' => 8,
    'columns' => 4,
    'category__in' => array ('35') 
    );
  return $args;
 }

but no success