Hamburger not opening on desktop

I’ve been using Sydney for a while. I had set it to use the hamburger on desktop and mobile. Recently (an update?) the hamburger stopped opening when viewing on the desktop. The class=“btn-menu” becomes “btn-menu active” but the menu doesn’t drop down anymore.

The website is

Not sure how it was working before but I followed this (all the way to the end) and now it’s working.