Hamburger Menus Issue

My menu works on mobiles and tablets but has issues on low resolution computers or those that like to split screen. The menu just doesnt click.
On full screen its ok and nice and big and then when its shrunk or on a lower res the hamburger menu comes in and doesnt work for like 600-900 pixels lower and higher its fine

https://www.bristolselfiestation.co.uk

Ive tried disabling all plug ins but it still has the issue. Im using sydney theme