Taps not working – is't not visible under what tab your at.

If you meant the menu item highlighting, then it only works with parent menu items. It doesn’t work with posts parent.

However, you can try this in custom.css:

.current-menu-parent {
background:#16A1E7;
}

It will highlight all parent categories in the menu.

I am very sorry the hear that, since the rest of your design is really great. Are you going to fix this in the near future, so that you follow usability guidelins for tab menus?

In WordPress users assign multiple categories in their posts, now if both these categories are in the main navigation bar then both will become highlighted which doesn’t look good that is why this code is not there by default.

If you want to do this for your site then you can use the code given above.