Sorry for necro-ing, but I have an issue with the same menu, might be CSS related as well.
I use similar menu. When display indicates .desktop.small they have icons and text underneath. On desktop everything behaves exactly as intended, but when I use tablet the submenu does not show up at all. Tried it on Safari, Chrome and Firefox browsers.
Anyone else encountered such issue? CSS nor JScript were not altered, therefore it should work normally?