Blank sitemap with no code in source

When I view my sitemap, the initial root sitemap page shows blank but has code in the source code, but when I follow the links to any of the post sitemaps, they show up completely empty, even in the source. I read the troubleshooting guide at http://kb.yoast.com/article/36-my-sitemap-is-blank-what-s-wrong, but it doesn’t give instructions on what to do if your sitemap shows up with no source code and you’re not using any specialty post.

I am using W3 Total Cache, which I followed the instructions in the troubleshooting guide for. We are also using google pagespeed service, and I feel that may be what is causing the issue, but I’m not sure how to fix that.

The sitemap can be found at http://www.seriousfiver.com/sitemap_index.xml

Any help or ideas would be greatly appreciated!

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