Primary Menu not showing any items in mobile view

Hello Catch Team First of all, thanks for the great theme. It looks great! I do have an issue, though. It came to my attention, that the Primary Menu does not show any items in mobile view. I'm able to expand the menu (the bar that moves in from the side), but it's empty. I've tested this on my Android phone with Chrome & Firefox and via developer tools in Firefox and Opera on my Windows & Linux workstation. The menu in Wordpress is configured via Appearance -> Menus and only contains Pages (no custom links or category entries). Also the pages don't contain any special characters, except for one space in one page title. I'm using a Catch Responsive child theme for the site. There are however only minor adjustments. I'll be glad to post them if you'd like. I'm using the most up to date version of Wordpress (4.3) as well as the theme (1.8) as of 19.08.2015 // 16:55 The site is http://www.beautycase-luzern.ch/ Any help or hints are very much appreciated. Cheers, Stefan