I have the same issue in the Dev environment (but not Stg or Prod). For us, yhe problem needs to be fixed by my org's Identity & Access Mgmt group. The certificate being sent has my old name within the credentials, which is why even if it's changed within Apptio, it will still revert back to the old name identified within the certificate (I just haven't gotten around to resolving this yet). Maybe the same in your environment?