Mobile Responsive Burger Menu Gone?

Has the mobile responsive show/hide option been removed?

On
https://treeandgardengiftcompany.co.uk/shop/ if you look at it on a smaller screen (adapt your window on a desktop) the filter turns into the 3 line burger menu so it’s hidden by default, when clicked it expands and shows. Then go back to desktop full size and it appears as default.

Has this option been removed. I am working on a dev site version of the above and it shows by default on both desktop and mobile.

We really need that feature back.