Hi LeonidS. Thanks for the reply but I am afraid you didn't read me well. I already know where that menu item is placed (Navigation->System->Toolbar member menu area) as I have already mentinned it on my post above. The problem is when I enable it from the admin side, it doesn't show in the toolbar in the front-end next to the Discussion, Notification, Search and Account icons. I don't know whether it is a bug or not.
Please. try to reproduce this problem here on UNA.io by enabling the 'Add Content' icon in Navigation->System->Toolbar member menu area, you will see that it doesn't work and you will see what I am talking about. Thanks.