Stream with transform not work in background

Question

In app, I use stream.transform and CombineLatestStream.combine3 from RxDart to combine and merge multiple three streams in app for button validation. It is work well but if app stay in recent and background for long a time. CombineLatestStream.combine3 not work and button not validate even all required fields are validate.

How this can be? How can I fix it? Here is my code for example

Controller code

  Function(String) get fillUserId => _userIdController.sink.add;

  Function(String) get fillPhoneNumber => _phoneNumberController.sink.add;

  Function(String) get fillPassword => _passwordController.sink.add;

  Stream<String> get userIdStream =>
      _userIdController.stream.transform(validateUserId);

  Stream<String> get phoneNumberStream =>
      _phoneNumberController.stream.transform(validatephoneNumber);

  Stream<String> get passwordStream =>
      _passwordController.stream.transform(validatePassword);

  Stream<bool> get submitValid => CombineLatestStream.combine3(
      userIdStream, phoneNumberStream, passwordStream, (u, p, pas) => true);

UI code

Widget loginButton(
      {required LoginBloc loginBloc, required bool isInternetAlive}) {
    return StreamBuilder(
      stream: loginBloc.submitValid,
      builder: (context, AsyncSnapshot loginSnapShot) {
        if (loginSnapShot.hasData) {
          formKey.currentState?.save();
        }
        return GradientButton(
          onClick: () {
            passwordFocusNode.unfocus();
            loginBloc.login(
              userId: userId!,
              password: password!,
              phoneNumber: phoneNumber!,
            );
            // passwordFocusNode.unfocus();
            _passCtrl.text = "";
            loginBloc.fillPassword("");
          },
          label: LOGIN_BTN_LABEL,
          isBtnDisable: loginSnapShot.hasData ? false : true,
        );
      },
    );
  }

And From UI use submitValid stream withstreamBuilder like that. But happening the error as above explanation. How can I fix?