Workflowmanager called only once (if at all) flutter

Question

I am using the flutter Workmanager and it is called only once, if at all.

@pragma('vm:entry-point')
void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) {
    debugPrint("Native called background task: $task");
    return Future.value(true);
  });
}

void initializeWorkManager() {
  Workmanager().initialize(
      callbackDispatcher, // The top level function, aka callbackDispatcher
      isInDebugMode:
          true
      );
  Workmanager().registerPeriodicTask(
    myIdentifier,
    myTaskName,
    frequency: const Duration(minutes: 15),
  );
}

initializeWorkManager();
runApp(
const ProviderScope(child: MyApp()),
  );

Even when the workmanager starts, it runs only once although my task is periodic.