Mobile navigation not clickable

Hi, we are redesigning our website and we found this really nice theme, which seems to be (almost) perfect for us. But now we have encountered one problem: In a multi-level main menu the submenu items are not clickable on my smartphone (Windows 10 Phone). When I tap on such a link, the menu just closes and nothing else happens. It seems that there is some JavaScript function which catches the click event (for closing the menu) and the actual link will not be clicked. On desktop PC, when I resize the browser to "smartphone dimensions", it works correctly (tested with Firefox and Edge). Also on an Android smartphone it works. Can you tell me, which JavaScript function is called when clicking a submenu link? I would try to disable the "close menu" function to see if this will help. Regards, Robert