On a WordPress 3.6 network, I can export an XML file from one site. Then when I go to a different site, on the same network, and use the importer to import that XML file, the importer stops and the page stops loading, so I get an incomplete page. For example, if I do a view source on the page, the last thing on that page is this: <h2>Import WordPress</h2>, so there's a lot of tags not closed.
I get no error whatsoever, and I see no evidence that the content has been imported.
Expected behavior: It just works, but if it can't, I at least get an error.