Hamburger menu stopped working on iPad or iPhone

Hi, my hamburger menu has stopped working on mobile devices; everything is fine on PC.
I’ve deactivated all plug-ins, cleared cache, deleted and recreated the main menu, and nothing has worked so far.
What’s going on?!
My website is https://www.isobelmoore.co.uk/
Thanks!

Ok, I’ve got it to work by deactivating the child theme. I hadn’t made any changes to the child theme yet, just set it up the other day.

Why would the menu in the child theme not work correctly? It was obviously a direct copy…?

I also noticed that the scrolling text in the header didn’t work in the child theme.