(I did try to add it to this post but the file type isn't permitted)
I've checked other sitemaps and of course they show the URLs quite clearly, so something is wrong with mine.
I tried disabling all add-ons and rebuilding the sitemap cache but I still get the same thing. I've never used a sitemap add-on prior to the addition in 1.4 so it can't be anything to do with that.
I'm not sure what the problem is or what next to check.