A ticked module is skipped when the module is not active on your account (for example Catering or Real Time Ordering without the module purchased), or for Wholesale when the logged-in customer has no wholesale locations. Also check you are looking at the right kitchen: Show on Header Menu can be set per kitchen location, so a kitchen-specific value can differ from the Global one. Finally, the Order dropdown itself only appears if Order is ticked in Pages to show on header (Theme > Navigation).