The problem happens when I try to link a pdf document in a button or any link field. When I update the edited page, blank page show up with the message: Forbidden, You don’t have permission to access this resource. But it is not true, I don’t have any problem with permissions.
The page builder that I am using is Unyson, I try to do the same thing with WPbakery page builder and everything goes well. So i think it is something to do with Unyson.