mwyche on "[Plugin: Yoast SEO] XML sitemap not working with Yoast plugin"

I am having the same issue as well on http://www.seeuncharted.com. Any assistance is appreciated.

I am also running my plugin on Nginx with Pagespeed enabled. Here are my rewrite rules:

#Pagespeed Location Directives

# Don't cache uris containing the following segments
        if ($request_uri ~* "/wp-admin/|/xmlrpc.php|wp-.*.php|/feed/|/|index.php|sitemap(_index)?.xml") {
                set $skip_cache 1;

#Yoast sitemap
location ~ ([^/]*)sitemap(.*)\.x(m|s)l$ {
        ## this redirects sitemap.xml to /sitemap_index.xml
        rewrite ^/sitemap\.xml$ /sitemap_index.xml permanent;
        ## this makes the XML sitemaps work
        rewrite ^/([a-z]+)?-?sitemap\.xsl$ /index.php?xsl=$1 last;
        rewrite ^/sitemap_index\.xml$ /index.php?sitemap=1 last;
        rewrite ^/([^/]+?)-sitemap([0-9]+)?\.xml$ /index.php?sitemap=$1&sitemap_n=$2 last;
        }