The Yoast SEO plug in XML index file for my site contains 3 distinct site maps for posts, pages, and categories.
The first two site maps are fine, however the category site map is actually generating HTML code and producing a page with a 404 error.
I found this out via Google webmaster tools alerting me with the error message: Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead.
Anyone else having this problem? Is there a fix?