I set up Restrictions but still can not see required menu item

First check the user role you defined for users at a sandbox. User role has higher priority over restrictions. If it is not allowed to add Pages with Subscriber user role you wont be able to permit this with Restrictions.
That's why we recommend to set Administrator user role for sandboxes and restrict access to certain section of the dashboard with Restrictions.

2. If you are sure that user role allows access to required section of the dashboard you should check whether you set up Restrictions for particular website. For this you should go to the dashboard of that website and set up restrictions for it. Thus you need to set up Restrictions for each sub-site that is used for registering sandboxes.