Responsive menu issue

Hey all,
im using theme Amadeus, ive been using this one for a couple of sites now.
usually i have no problems at all with the menu. but currently, when opening the site from a mobile phone, menu displays just fine, but nested menus will just not expand if i hit the item name, I must specifically hit the ‘+’ next to it. Im using custom links with no link in order to just create an item with no page. I did the same on previous sites but its just not working properly now.
anyone know how to make it expand when hitting the name too?
thank you