Theme Mystile (no Sale display?)

This plugin enhance the existing sale badge, so if it is not showing in any theme then the issue is in the them itself. That being said, I don’t know of any issue with Mystile, but you’ll have to check with WooThemes directly about that.

I also had to look for it.

In wp-content/themes/mystile/includes/theme-woocommerce.php (make a copy into a child theme) you have to comment out this:

// Remove sale flash on archives
remove_action( 'woocommerce_before_shop_loop_item_title', 'woocommerce_show_product_loop_sale_flash', 10 );