There have been reports with Google's Blogger tool and Sitemaps not working well together. A Google Groups thread notes that those submitting a Sitemap file to Google Webmaster Tools, and using Google's Blogger service, are having issues.
Many who have submitted a Sitemap notice their Sitemaps are still pending as of August 1st.
Interestingly enough, we covered a similar topic last week, which seems to be very related. Can it be the Sitemap causing the issue or something else. Why has Google stopped crawling these Blogger or Blogspot blogs?
Googler, JohnMu, replied to the thread saying they are looking into it:
I just wanted to mention that we have been looking into this. As soon as I have more information, I'll let you know. It's great to see you all using Sitemaps!
At this point in time, the Google Groups area for Blogger Help is having issues and I cannot seem to access specific threads to learn more.
Until we know what is up, I really do not know where to answer the question. I promise to keep watching and either update this post or write a new piece on this weird Google/Blogger issue.
Forum discussion at Google Groups.