Drop Down Menu (in lumi subtheme) opens all levels on certain pages

Hello,

I know the author appears to be gone for awhile, but I'm trying to get the lumi arctica subtheme working and I'm having some problems with the drop down that I was wondering if anyone came across a fix for....

On the user/register and /contact pages (all others appear fine), the drop down menu opens (expands) all the menu items and fills the page (see attached screenshot)

Any idea how to debug this?

Thanks!