Problem solved

[Edyap]

I'm posting this separately so it's not hidden in the replies and forum visitors can see it.

My problem, as I outlined in my post, was that the Hamburger Menu froze when a visitor navigated to a page and scrolled down/up. The act of scrolling down made the Hamburger Menu "lose its bearings." This was because I set the menu to "Position: fixed" so it would remain visible.

I figured the problem was in the javascript, and I went over it (crawling blind, as I don't know javascript).

Finally I tried turning off the option to put the mobile menu BELOW the Hamburger icon. The default, if this box is not checked, is to put the mobile menu flush with the top of the screen/page. Yes, that option can be turned on and off in the javascript too.

It worked. The Hamburger menu no longer freezes. It does cover up the navigation bar (and logo above or below it), which I don't prefer, but at least it works.

At any rate, in the meantime I had to insert another navigation bar picked up from online creators.