LsaGetLogonSessionData API returns session data without logonServer

Question

I am using LsaGetLogonSessionData to retrieve the logonSessionData on a machine that is using AD and Kerberos in a Domain Controller as a login method. However, the logonServer field is empty in logonSessionData. But from commandline, I'm able to get the logonServer by using nltest/dsgetdc or set l command. Anyone knows why I am not able to get logonServer from the code?

Attaching code snippet as below:

PSECURITY_LOGON_SESSION_DATA logonSessionData;
  for (ULONG i = 0; i < logonSessionCount; i++) {
    if (::LsaGetLogonSessionData(logonSessionList + i, &logonSessionData) != 0) {
      LsaFreeReturnBuffer(logonSessionList);
      DWORD error = ::GetLastError();
      LOG_ERROR("GetActiveLogonUser: LsaGetLogonSessionData failed ", error);
      return error;
    }

    if (std::count(sessions.begin(), sessions.end(), logonSessionData->Session) &&
        (logonSessionData->LogonType == Interactive || logonSessionData->LogonType == RemoteInteractive)) {
      const std::wstring logonServer = logonSessionData->LogonServer.Buffer;
      if (!logonServer.size()) continue;

      std::wstring domain = logonSessionData->LogonDomain.Buffer;
      std::wstring userName = logonSessionData->UserName.Buffer;

      logonUsers[StringUtils::GetStringFromWString(domain + std::wstring(TEXT("-")) + userName)] =
          logonSessionData->Session;
    }
  }