User Permissions need to be configured for full access to Landing Pages. Verify that the Organization Administrator User Account has Landing Pages - full access checked under User Permissions in the User Accounts menu. Click Save, the User Account now has access to the full Manage Site menu.
Note: If the user is logged in during the time when the change is made, they need to log out of Acoustic Campaign and log back in before the changes take effect. The same process applies for disabling full access to Landing Pages.