Hello,
We checked your site using the default Storefront WooCommerce theme and faced the same issue https://gyazo.com/5f876aeef04cf565d6c915739c1b5a41 So, our theme is not the reason of the registration problem. Contact WooCommerce support to get help with this https://wordpress.org/support/plugin/woocommerce/ We are able to help only if the problem caused by our theme.
Regards
