As a quick temporary solution i replaced plugin files from backup (17 of june) – before last upgrade was done, at least no errors i see in sitemaps now.
And will wait for updated version with fixed bugs. Maybe will create a test blog to upgrade monitor when issues are fixed then will upgrade main blog. Thats the only thing comes to my mind as a solution
I also have same issue.
I bet its something in relation to nextgen gallery and sitemap.
<image:loc></image:loc> in sitemap is empty now, instead of having a link to images (issue appears only to nextgen gallery images, when default wordpress images are ok)
Here is a screenshot
