Mega menu failure on staging site

I use the “mega-menu” css for my live site ( I cloned the live site (on SiteGround). However, the mega-menu css has no effect on my clone. In examining the produced code the menu items all had “fl-has-submenu mega-menu-disabled”

id=“menu-item-32012” class=“menu-item-small menu-item menu-item-type-custom menu-item-object-custom menu-item-has-children fl-has-submenu mega-menu-disabled” aria-haspopup=“true”>

<ul class=“sub-menu” style=“”

What am I missing?

An update. I discovered that, while I was inspecting the source code of the published page it had gone into it’s small device mode. That was the cause of the fl-has-submenu mega-menu-disabled

When I expanded the view to see the large site that setting was not present. So, that is not the cause of the problem.

Anyone have an idea of what might be going on?

Thanks, Matthew