The IE browsers on Windows 8 touch devices and WP8+ are not the same - they come from the same code base, but Microsoft cuts some features and adds others to make them usable on phone devices. Additionally the underlying OS is also different. Coincidentally the last thing that was added in the last WP8.1 IE11 update were WebKit-style touch events which I suspect are the reason the Menu works there and not in tablets, which uses the IE PointerEvent model only. On the plus side, the issue was fixed
and tested and will be released with the next internal build, probably today. Let me know if the fix works for you.
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