port80services on "Responsive menu does not work - first go anyway"

I have 2 websites I am building at the moment, both using this theme. I've noticed on both of them that there's an issue with the responsive menu. After page first loads, if you resize the browser window so the toggle button appears then click on it, it does nothing. If you then refresh the page, it works. My sites are local so I cant test on a tablet, but I assume the toggle button won't work on tablet either until a page is reloaded.

My best guess is this is a CSS issue and due to the use of the !important in style.css here -

@media (min-width: 769px) {
#site-navigation .menu-primary-container,
#site-navigation div.menu{
display: block !important;
}
}
- which coud cause issues with the jquery controlling the nav.

Be grateful if you could test and see if you get this bug too, and see if it can be fixed. As I say, I've 2 sites on the go and the same bug is in both and I've barely customised one of them at all.

Thanks

Will