Show friendly permalink URL for posts

I’ve noticed something a little strange on my newly created sitemap. When I hover over the links listed under the “Pages” header, I see the friendly permalink URL. Example: http://domain.com/contacts

But when I hover over the links listed under “Posts”, I see URL’s that look like this:
http://domain.com/?post_type=post&p=3240

That’s the strange part.

If I click on the link, the “ugly” URL somehow resolves itself to a friendly URL and the page is displayed. An example of the resulting friendly URL: http://domain.com/10-reasons-to-donate/.

Is there a way for the Simple Sitemap plugin to display the friendly permalink URL instead of the “ugly” URL?

https://ww.wp.xz.cn/plugins/simple-sitemap/