YITH WooCommerce Badge Management – Badge not showing !

Add this code to the functions.php file of your theme, at the end of the file. You can also find the file in Appearance > Editor > Theme Functions (functions.php)
add_filter( 'woocommerce_single_product_image_large_html', array( YITH_WCBM_Frontend(), 'show_badge_on_product_thumbnail' ), 99 );