I have had a user with browser role which has been able to make subscriptions but he has not seen CC and BCC fields. Because of that, I added Content Manager role for him to all folders and reports and after that, he cannot make more subscriptions or manage reports in any way. He gets error "The permissions granted to user 'domain\username' are insufficient for performing this operation". Now he can only see the reports.
Do you have any idea?
Browse to Site Settings, Configure item level role definitions. Then check what settings you have for Content Manager. Maybe someone removed them.