Badge showing behind product

Hi

I installed the plugin but the badge, or what I think is the badge appears to be showing behind the product https://midlandspkakickboxing.com/product-category/seminars-tournaments/ (Nationals Product)

I have added the code to the custom css as suggested in another post but this did not make any change –

soldout {
z-index: 999999 !important;
}

Thanks in advance

Lee

https://www.ads-software.com/plugins/woocommerce-sold-out-products/