Add link gone from main menu and getting errors when trying to add new menu item

Question

Running D7

For some reason the add link is gone from the admin menu view...can only edit but can't add any links or menu items, getting errors also:

Warning: Illegal string offset 'hierarchical_select' in 
drupal_array_set_nested_value() (line 6776 of 
C:\aquiasites\redoII\includes\common.inc).

Fatal error: Cannot create references to/from string offsets nor 
overloaded objects in C:\aquiasites\redoII\includes\common.inc on line 
6776

I disabled hierarchical_select to no avail...I can't find the view to control those settings, but this is a core view right?

Usually menus say:

    list links    edit menu    add link

But now these options are gone...

It only says:

    MENU LINK   ENABLED TARGET  OPERATIONS

Answer 1

Ok, found the answer, eventually another error popped up when trying usermenu:

Warning: Illegal string offset '#value' in 
content_menu_form_menu_item_delete_form_alter() (line 270 of 
C:\aquiasites\redoII\sites\all\modules\content_menu
\content_menu.module)

I disabled all possible menu plugins...the offending module didn't create any errors on main menu and other, ONLY on usermenu...

Disabled this module https://www.drupal.org/project/content_menu

Now works fine