MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
That might be a known bug, you need to reload page every time you view new file. I'm planning on fixing it pretty soon. If it doesn't help I'd appreciate if you could share the files you are trying to view and OS/browser versions.