Mobile menu

I have a website that hides the top navigation menu when views on a small browser in a hamburger menu.

The problem is it no longer shows the 4th level of navigation tier when it shrinks. Using Firefox, when you click on the 3rd level, it attempts to drop something down but it doesn’t do it. It shows when it’s full screen however.

It should be (1st level) About – (2nd level) Leadership – (3rd level) Board of Trustees – (4th level) Agendas and Minutes, etc.

We had a vendor create this website and they are no longer answering our emails/phone calls so I have no idea how to go about fixing this error.

Drupal version: