Android : Android logging started apps with Android L

For my Masters Thesis I´m developing an Android logger which should log, besides other parameters, which apps get started by the user. So I got a running Service and my app is not in the foreground. At the moment I´m doing this by triggering an broadcastreceiver

public void AppAlarmManager(Context context) {
    Log.i(TAG, "AppAlarmManager");
    AlarmManager ama = (AlarmManager) context
            .getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(context, AppReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0,
            intent, PendingIntent.FLAG_CANCEL_CURRENT);
    ama.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(),
            (2 * 1000), pendingIntent);
}

In the broadcastreceivers onReceive method I´m calling this method:

    public void getAppName(Context context) {
    // Log.i(TAG, "getAppName");
    acm = (ActivityManager) context
            .getSystemService(Context.ACTIVITY_SERVICE);
    List<ActivityManager.RunningTaskInfo> taskInfo = acm.getRunningTasks(1);
    for (RunningTaskInfo runningTaskInfo : taskInfo) {
        PackageManager pm = context.getPackageManager();
        ComponentName comName = runningTaskInfo.baseActivity;
        String Packname = comName.getPackageName();
        try {
            ApplicationInfo appInfo = pm.getApplicationInfo(Packname, 0);
            applicationName = (String) (appInfo != null ? pm
                    .getApplicationLabel(appInfo) : "(unknown)");

            packageName = pm.getApplicationInfo(Packname, 0).packageName;
        } catch (NameNotFoundException e) {
            e.printStackTrace();
        }
    }....}

and then I can write the app name in my database.

Up to Android 4.4.2 everything is working flawless and all started apps are listed in my database.

But since i put Android L on my Nexus 5 only the first app after my App gets closed (mostly the Launcher) gets written to my database and the broadcastreceiver will not be triggered until I open my app again.

So you got any suggestions what I can do to log started apps with Android L?