Nginx xml sitemap load like html in blank page

Hi to all i try to create the sitemap xml with yoast but when i go to the page http://ntacalabria.it/sitemap_index.xml i see a blank page. But if i see the source code i can see the html sitemap index generated and if i use the url http://www.ntacalabria.it/index.php?sitemap=1?sitemap=1 i have also the blank page but the source code see the xml index generated.

Thi si my configuration file for my site..

server {
    listen *:80;
    server_name www.ntacalabria.it ntacalabria.it;

    access_log /var/log/nginx/wordpress.access.log;
    error_log /var/log/nginx/wordpress.error.log;

    root /home/ftp/wordpress;
    index index.html index.htm index.php;

    include /etc/nginx.wp/restrictions.conf;
include /etc/nginx.wp/wordpress.conf;
rewrite ^/sitemap_index\.xml$ /index.php?sitemap=1 last;
rewrite ^/([^/]+?)-sitemap([0-9]+)?\.xml$ /index.php?sitemap=$1&sitemap_n=$2 last;
    location ~ [^/]\.php(/|$) {

        # Zero-day exploit defense.
# http://forum.nginx.org/read.php?2,88845,page=3
# Won't work properly (404 error) if the file is not stored on this server, which is entirely possible with php-fpm/php-fcgi.
# Comment the 'try_files' line out if you set up php-fpm/php-fcgi on another machine.  And then cross your fingers that you won't get hacked.
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;

        fastcgi_index index.php;
        include fcgi.conf;
        fastcgi_pass unix:/var/run/php-fcgi-wordpress-php-fcgi-0.sock;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

    }

}

Thank you

Ps the sitemap was generated i can’t see it only (and google)

https://ww.wp.xz.cn/plugins/wordpress-seo/