Why is the mobile menu not visible in Symmetry theme?

[jaclynhope]

Using Symmetry: When you click on the mobile/hamburger menu, the screen dims but no menu appears. I've played with every setting, tried every combination of variables. I only have one additional app (Wishlist Hero) which I've uninstalled and reinstalled to see if there was a conflict, but it didn't make a difference. I haven't messed with the theme's code at all other than a few changed background and heading colors, and that was done in the builder on the CSS input field. 

Please let me know what could be interfering, where I should look, what I should try. Maybe it's the Java...? I reached out to the theme's developers and they weren't helpful. I'm stuck.

Site: esthersky.com