Mobile Menu Only opens briefly

Forgot to say the URL for the site is https://msuth.co.uk/hosted/gymnastics/dev/

Hey,
This means you have a plugin overriding the collapse functions of the theme.

Here is some css you can use to force it to work even with the plugin installed on your site.

Go to appearance > theme options> advanced settings and add this css:

.kad-nav-collapse.in {
    height: auto;
}

Kadence Themes

Thanks so much for your help!