iphone 6 hamburger menu not opening

I don’t think this is just a problem with Enfold but maybe you can help me fix it.
Sometime in the past few months or year (?) neither of the browsers (Firefox, Safari) on my iphone 6 will open hamburger menus on seemingly any site including the new Enfold site I just made. I thought maybe it’s because the iOS is so old (iphone 6 can only go up to version 12.5.7). But in searching on this problem it turns out a zillion people are having this problem on very new iphones with much later iOS..
On my new Enfold site, when I touch the hamburger menu the screen in that corner blinks but the menu doesn’t open.
jeffersonbaroque.org
I noticed that after I touch the hamburger, the address line changes from the address above to
jeffersonbaroque.org/# as if the code is directing the browser to an anchor on the same page. But my menu items are separate pages from the home page.
On other sites where the hamburger menu also doesn’t work (most of them), the # doesn’t appear in the address after touching the menu.
I did a soft reset of the phone and I cleared the cache in both browsers. Nothing changed.
In trying to find help by searching the web, I turned up this:
https://developer.apple.com/library/archive/documentation/AppleApplications/Reference/SafariWebContent/HandlingEvents/HandlingEvents.html
and this:
https://stackoverflow.com/questions/54236221/responsive-hamburger-menu-not-working-on-mobile-safari/54290816#54290816
but I am not a programmer so it all means nothing to me.
Has anyone else had this problem?