Hi
i do not know if the mega menu not working because is free version, the sub menu not working. I can showing the sub pages, why?
the setting of the page by mega menu showing this message:
Mega Menu can only be created on top level menu items
You can only add a mega menu to your top level menu items.
Go to Appearance > Menus, hover over one of the top level menu items (the one you want to add a mega menu to) and click the blue Mega Menu button. Then set sub menu display mode to ‘Mega Menu’.