I have installed the latest version and run it using a cron job (it still stopped, and I had to resume).
Anyway, I validated the results with your XML Validation.
No problem with sitemap.xml, also validated by another website
Problem with sitemap_images.xml, but validated as ok by the other website
So your software validator says the result of the USG has errors, the subject of this post.
You can see it yourself when you validate [external links are visible to admins only]
In the meantime, I will try to recrawl again, in my other server where I run this program.