StreamBuilder is not rebuilding on new event in stream

Your bloc needs to be a type of Stream. The same stream type as your StreamBuilder. For example your bloc needs to be a Stream<Alarm>. Otherwise stream: widget.bloc.alarmController.stream, will only be called once and won't act as an asynchronous stream of data.

Your Streambuilder needs to check for connection states

Widget build(BuildContext context) {    print("rebuilding..."); // as of now this gets called only on view initialization and never again - i.e. not on new events going through alarmController.stream    return StreamBuilder<Alarm>(        stream: widget.bloc.alarmController.stream,        initialData: Alarm(''),        builder: (BuildContext context, AsyncSnapshot<Alarm> snapshot) {          if (snapshot.hasError) return new Text('Error: ${snapshot.error}');      switch (snapshot.connectionState) {        case ConnectionState.waiting:          return Text('Loading...');         default:           if (!snapshot.hasData) {             return Center(                child: Text(StringLiterals.NO_ALARM_DATA_MSG))             );          }         return Switch(              activeColor: Colors.red,              value: snapshot.data.status == 'Started',              onChanged: (bool _value) {                _newAlarmValue = _value;                _askAlarmConfirmation();              }));      }

Here are the other types of connection states you can check for:

async.dart

    enum ConnectionState {  /// Not currently connected to any asynchronous computation.  ///  /// For example, a [FutureBuilder] whose [FutureBuilder.future] is null.  none,  /// Connected to an asynchronous computation and awaiting interaction.  waiting,  /// Connected to an active asynchronous computation.  ///  /// For example, a [Stream] that has returned at least one value, but is not  /// yet done.  active,  /// Connected to a terminated asynchronous computation.  done,}

The issue was I was instantiaing my BLOC incorrectly(second one) and working on a second parallel stream and therefore not the one passed to StreamBuilder.