Mobile menu drawer issue

Hi, our mobile menu isn't opening up on some pages, however opens up fine in others.

An example of a page that it works on are the product pages here > https://www.teyboutique.com/collections/baby-boy-gifts/products/personalised-blue-star-white-hooded-baby-towel

However, it won#t open properly on our homepage and collection pages.

Can you fix straight away for us? It worked fine this morning so we are thinking it's a very small code changed needed.

Emma