exclude author from sitemap not working

A couple of things:
1. When I check the box under the user profile settings to exclude user from author site map, and update it, the box goes back to being unchecked.
2. Why is this even an option for subscriber profile accounts in WP? Shouldn’t it, by default, be the opposite, where it does not automatically add them to sitemap, if they’re just a subscriber?!

https://wordpress.org/plugins/wordpress-seo/