Sitemap being weird

I installed this plugin and it shows sub-sitemaps and that fine in Google Webmaster Tools for my www domain, but I also have my non www domain on Google Webmaster Tools, and the non www domain shows, that sitemap.xml submitted, but when clicking the link to show the pages indexed, there is blank page. On the www domain works fine. I was using all in one seo pro pack with the sitemap plugin and did not have any problem until this one installed.

So why doesn’t both domains that are exactly the same either www or without not show sitemap for both in Google Webmaster Tools?

https://wordpress.org/plugins/google-sitemap-generator/