I recently installed Yoast SEO. I configured it to noindex Media files. I'm using the sitemap feature, but WebMasterTools gives me a "warning":
Sitemap contains urls which are blocked by robots.txt.
The examples of these blocked files are all image files which are used in the posts the sitemap links to, which are stored in wp-content/uploads. I did have the wp-content folder blocked, so I unblocked it. After a day or so, Google cached the new robots.txt file, which blocked wp-admin and wp-includes but not wp-content. I'm still getting these warnings.
Any idea what's happening? I tried changing the plugin to index the Media files, but that didn't fix the errors. I would actually prefer to block ALL my wp backend files in robots.txt, including the image folder. I don't understand why this is happening, or how to fix it.