woocommerce hook doesn't run on main shop page

the woocommerce_before_shop_loop action doesn’t seem to run in loop-shop.php when a product category isn’t selected.

for instance — for the /shop/ page, it does not show the sort filter, but on shop/product-category/earrings/ page, it shows the sort filter as it should. any changes to that action only affects the product category pages, not the unfiltered main page.

does anyone know a reason why this hook wouldn’t work for the main page?