One page menu mobile issue

Hi,
I have set up a one page site, but in mobile view there is a problem with the menu: clicking on the hamburger anchors a blank screen is displayed and you cannot scroll or do anything else.

The same problem is also detectable on your site: https://www.awesomescreenshot.com/video/2945409?key=4543e9786dfe18df2cb6f6753655cdb9

How to fix?

Thanks,
Francesco.

The page I need help with: [log in to see the link]