Flutter workManager callbackDispatcher starts but do not finish the exrcution of a asynk function

Question

Flutter workManager callbackDispatcher starts and calls the below function. But never finish it.

static Future<List<Map<String, dynamic>>> getItems() async {
  debugPrint("In getItems");
  final db = await DatabaseHelper.db();
  final a = db.query('items', orderBy: "id");
  debugPrint("post query, before return");
  return a;
}

If I call the function onPressed it works fine. If I call the same function from callbackDispatcher it Start and print "In getItems" but not print "post query, before return".

Getting no error message either.

I have registered it as one off task.

Workmanager().registerOneOffTask("task-identifier", "simpleTask");

Future<void> callbackDispatcher() async {
  var sm= SmsSender();
  Workmanager().executeTask((task, inputData)  {
    try {
      sm.getAlertBookings();
      smsCompleter.complete();
    } catch(err) {
    print(err.toString());
    throw Exception(err);
  }
    return Future.value(true);
  });
  await smsCompleter.future;
}

What is causing this issue and how can I fix it?

I tested the same function onPressed it worked fine. callbackDispatcher Start the function but do not finish it.