It appears it may be a jquery issue. Have you tried updating to the latest jquery version? It looks like your page has several jquery versions loaded on the page. I'd remove all but one and try a newer version. You have several instances of 1.8.1 and 2.1.3 listed on the page.
I'd clean that up to have only one version of jquery and try using version 3.3.1.
This is something I'd really need to spend some time debugging to fix, but I'd probably start there.
Maybe add just the menu to a blank page with just one jquery version to see if the latest fixes the problem.