Responsive menu not working

My site http://casadelrey.no/ has been working nicely with Catch Everest Pro for a few years and I have regularly upgraded to the theme’s latest version. Recently I was informed the that the menu wasn’t working on iPhone iOS 10.2.1. I have tested on Android and it is working ok there. Is this a known issue and how can I fix the problem? Also, it would be nice to have the option to choose whether the menu on mobile devices is displayed collapsed instead of as a long list. That would be similar to the desktop’s dropdown menu.