Preload does not work (I am using Nginx)

I am using WP Super Cache version 1.4.8 with Nginx.

Important part of the nginx.conf:

	server {
		server_name testingtestingtesting.tld www.testingtestingtesting.tld;
		listen 192.168.100.42;
		root /home/account94/public_html;
		index index.html index.htm index.php;
		access_log /var/log/virtualmin/testingtestingtesting.tld_access_log;
		error_log /var/log/virtualmin/testingtestingtesting.tld_error_log;

# upload import file fix
client_max_body_size 20M;

		fastcgi_param GATEWAY_INTERFACE CGI/1.1;
		fastcgi_param SERVER_SOFTWARE nginx;
		fastcgi_param QUERY_STRING $query_string;
		fastcgi_param REQUEST_METHOD $request_method;
		fastcgi_param CONTENT_TYPE $content_type;
		fastcgi_param CONTENT_LENGTH $content_length;
		fastcgi_param SCRIPT_FILENAME /home/account94/public_html$fastcgi_script_name;
		fastcgi_param SCRIPT_NAME $fastcgi_script_name;
		fastcgi_param REQUEST_URI $request_uri;
		fastcgi_param DOCUMENT_URI $document_uri;
		fastcgi_param DOCUMENT_ROOT /home/account94/public_html;
		fastcgi_param SERVER_PROTOCOL $server_protocol;
		fastcgi_param REMOTE_ADDR $remote_addr;
		fastcgi_param REMOTE_PORT $remote_port;
		fastcgi_param SERVER_ADDR $server_addr;
		fastcgi_param SERVER_PORT $server_port;
		fastcgi_param SERVER_NAME $server_name;
		fastcgi_param HTTPS $https;

# BEGIN GZIP
gzip on;
gzip_disable "msie6";
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/html text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/javascript;
# END GZIP

set $cache_uri $request_uri;

# POST requests and urls with a query string should always go to PHP
if ($request_method = POST) {
    set $cache_uri 'null cache';
}
if ($query_string != "") {
    set $cache_uri 'null cache';
}

# Don't cache uris containing the following segments
if ($request_uri ~* "(/wp-admin/|/xmlrpc.php|/wp-(app|cron|login|register|mail).php
                      |wp-.*.php|/feed/|index.php|wp-comments-popup.php
                      |wp-links-opml.php|wp-locations.php |sitemap(_index)?.xml
                      |[a-z0-9_-]+-sitemap([0-9]+)?.xml)") {

    set $cache_uri 'null cache';
}

# Don't use the cache for logged-in users or recent commenters
if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+
                     |wp-postpass|wordpress_logged_in") {
    set $cache_uri 'null cache';
}

# Set the cache file
set $cachefile "/wp-content/cache/supercache/$http_host/$cache_uri/index.html";
if ($https ~* "on") {
    set $cachefile "/wp-content/cache/supercache/$http_host/$cache_uri/index-https.html";
}

# Add cache file debug info as header
add_header X-Cache-File $cachefile;

# Try in the following order: (1) cachefile, (2) normal url, (3) php
location / {
    try_files $cachefile $uri $uri/ /index.php;
}

#        location / {
#			try_files $uri $uri/ /index.php?$args; 
#        }
		location ~ \.php$ {
			try_files $uri =404;
			fastcgi_pass unix:/var/php-nginx/148519495327014.sock/socket;
		}
		listen 192.168.100.42:443 ssl;
		ssl_certificate /home/account94/ssl.cert;
		ssl_certificate_key /home/account94/ssl.key;
		listen [::];
		listen [::]:443 ssl;
	}

Screenshots:

It says that creating cache files is working, but files are not created.

Cache files are created without problems when anonymous users visit the website.