I've run into a strange issue where (only on the Shopify site after conversion) a dropdown menu item seems to be open by default. On Desktop it's perfectly fine, it's just at 991px breakpoint and below. (The empty dropdowns in the menu on desktop are because we're trying to get mega menus to work)
Sorry.. got ditracted. So the main problem ist, that you have li-section on the nabar element itself. Webflow ads a lot of attributes to the navbar elemets which shopify cant render. So you need to wrap the navbar elemt inside a div and add the li-section there. I made an example inside your webflow project (Section / Navbar-New).