Hello,
We would like to report an incompatbility issue with the gkMobileMenu (which took us a while to track down), which causes the mobile menu to no longer show up. When you inspect the code, it appears to be modified to a random ID and style "display: none" added inline.
The problem is caused by an incompatibility between gkMobileMenu and the "Chosen" jQuery plugin (http://harvesthq.github.io/chosen/) included in Joomla Hikashop and we suppose other joomla extensions. The plugin beautyfies dropdowns and doing so it ruins the mobile menu, which is of course "ugly" in order to have the default behaviour on mobile.
You can disable "Chosen" on the "gkMobileMenu" by adding class="chzn-done" to it, making "Chosen" believe it has already processed the menu and thus leave it alone.
LP,
Jure