problem with sticky menu

Hello,

Just purchased this and working through some issues on my team’s site:
https://www.videogamesjapan.com

The sticky menu works okay but when scrolling down the perfectly adjusted menu it pushes one menu tab to the next line in sticky mode. You’ll see what I mean on the site.

I’ve tried using ‘max-width 1280px;’ in the CSS but it gets overridden on refresh or when returning to the top of the page, making the sticky menu and site overall really ugly.

Anyone have any ideas how to rectify this?

https://www.ads-software.com/plugins/megamenu/