Header Secondary Nav

Same in my case and I posted a note about it here as well:
https://wordpress.org/support/topic/mobile-menu-does-not-work-3

and Ion from the support promised to submit the issue to the developers, although it may take time to get it fixed.

So in the meantime I found a great menu plugin that is just great and works on mobiles as well, try it: https://wordpress.org/plugins/megamenu/

and check it on my website: http://memoryisourhome.com/

Marek