to reproduce:

• create a new user with edition permissions(editor is good)
• login with that user
• open any object
• the contents tabs are disabled, and the button on the left is set to '+'. clicking it will not do anything
• navigate to any other object, the tabs are working
• go to the object with the bug again. edit->publish, the problem is fixed

the problem never shows up again, it's only on the first opened object by a new user