I've just noticed something "similar" in firefox, with an exported project in local.
Firefox ask me if I want to save datas for an offline use.
As it is local (double clicked on the html file to execute it), I can't say yes. And when I try to go to the next layout, it freezes.
Nevertheless, during previews everything worked fine happily, and it also works when the exported project is hosted online (dropbox).
Maybe this is not related at all, but it felt like it though (file mode ?).