There are many features in IE10 that aren’t present compared to a modern browser. And some features can’t be added, even Microsoft can’t, all they can do is replace them over and over. The theme is evolving, getting more features and there will be the time that’s we’re going to drop old browsers as we move forward. Other developers updated their browsers, but with Microsoft, it’s stagnant and always bound to the Operating System.
Hence, it’s up to you if you wish to use themes that have modern features, or themes with minimal ability. But I did check it in IE10 and the menu is displaying okay. So maybe it also depends on Operating System KB Updates (bound to OS) and since Microsoft already drop supports for IE10, then there is no way we can really confirm it in every KB Updates.
And yes, it should work with any shortcode, unless the shortcode doesn’t follow Wordpress standard. Should be using
return instead of