Strange behavior in the top link bar and open in a new tab

Hello,

I am having a strange behavior in the top link bar. Every element in the menu has the "open in a new tab"-option checked and is working fine but is not working at all in a sub site which inherit the menu. 

I have look at the code thinking that the menu in the sub site did't get the target="_blank" but is there.

Anyone who knows what can be happening?

Thanks!!!! 

Discusion actualizada