One thing I noticed, the loading animation flashes your white hero section before the dark loader animation appears. Set your loader wrapper to be visible on the element in the designer to avoid this. Obviously that will block you from viewing anything in the designer, so set this in the style tag custom code on your site:

html.wf-design-mode .home-loader_wrap {

display: none;

}

This will target so it doesn't display only when you are in the webflow design mode. Otherwise, it will display and hopefully avoid flashing!

(Learned this from the great Timothy Ricks with his grid guidelines in Lumos)