Not sure if the last WC update or the last Legenda update caused this but for variable products, quantity entry is not possible on the product page.
I changed in the theme /woocommerce/global/quantity-input.php to fix.
I added line 33: to show the quantity because it was set to hidden.
This allows quantity entry. but the <> buttons don’t work.
I have the same issue with the Storefront theme, so I suspect it’s a WC thing.
I also tried disabling all plugins except WC.
Is there anything else that can be done to return to normal functionality?