Mobile Menu Disappeared

I love this add-on and would like to buy the pro version, but I’ve had a problem with the free one that I’m not sure the Pro would fix.

I have the logo grid on my homepage, but on the mobile version, my site’s responsive menu disappears (i.e. the three white lines disappear…the menu is still there and works, but there’s nothing to indicate that it is there).

It’s definitely this plug-in that is causing the issue, because when I deactivate it the three white lines are visible again.

Any ideas?

The page I need help with: [log in to see the link]