Did you end up getting this working?
I’m having the same problem. I did have google sitemaps working, but now I’m also getting the white page. When I look at the generated file, it starts the document, but stops before it gets to the end so never has a closing tag. You can also see this in browser web inspector.
I thought it was an interaction with a module or config and have stepped through a new installation bit by bit to try and work out what’s causing the issue, to no avail.