Search and Mobile Menu Not Displaying in Child Theme

Hello,

I’m currently working on a site (https://www.loveboundpromotions.com) running WordPress 4.6.1 and I’ve created a child theme for it based on the Identity theme from the WordPress directory.

I’m having some trouble with the primary navigation menu and search function though. It works perfectly when the parent theme is active but when I activate my child theme it stops responding as it should.

The menu itself, together with the search icon, is visible in browsers on my desktop PC and the menu links work fine. However, when I click on the search icon, nothing happens.

This is the same in landscape view on my iPad but when I rotate it to portrait, the menu collapses into the button which simply changes it’s appearance when tapped but doesn’t drop the menu down, as it does in the parent theme.

At first, I thought this would be something to do with the modifications I’ve made in the child theme, either in the CSS or the few small changes to my header and footer templates. However, to clarify this, I tried creating a new, temporary child theme, with just the theme headers in the CSS file, and the menu broke instantly, without any further changes or any other custom template files.

I have also tried creating a child theme from the default Twenty Sixteen WordPress theme and the menu and search work absolutely fine so this obviously isn’t happening with all child themes.

I’d be very grateful for any suggestions anyone might have.

Thanks in advance,

Jon