.NET SystemEvents method not fired when starting a new process from within app

Question

Basically, this question also summarizes my issue: SystemEvents.SessionEnding not fired until a Process (opened before) gets closed

But there is no answer to it yet. I have a Console app that starts another process from within itself. The app also listens for SystemEvents.SessionSwitch. If I comment out the code that starts the additional process, the event handler for SessionSwitch is hit. However, if I uncomment the code that starts the additional process, the handler is not hit. I'm 100% confident that the event handler not being hit is due to starting a new process from within my app... I just don't know why.

I tagged this as a possible multithreading issue because that's what some of the comments made in the question posted above seemed to indicate. However, I'm not sure at all what could be causing it.

Here's some of the code.

 [STAThread]
 static void Main(string[] args)
 {
        SystemEvents.SessionSwitch += SystemEvents_SessionSwitch;

        _myFoo = new _myFoo();
        _processManager = new ProcessManager();

        // If I comment out this code block, the SessionSwitch event handler is hit
        // ------------------------------------------------------
        if (args.Length == 0)
        {
            // creates a duplicate process to monitor the current (main) process
            _processManager.StartObserverProcess();
        }
        else
        {
            // start monitoring the main process
            _processManager.ObserveMainProcess(int.Parse(args[0]));
        }
        // ----------------------------------------------------

        _myFoo.Start();
  }

// this method does not get hit if we start the 'duplicate' 
// monitoring process from within ProcessManager
private static void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
{
        if (e.Reason == SessionSwitchReason.SessionLock)
        {
            // Do something when session locked
        }

        if (e.Reason == SessionSwitchReason.SessionUnlock)
        {
            // Do something when session unlocked
        }
}

The ProcessManager basically starts another 'duplicate' process that watches to see if the current process exits (I know the term 'duplicate' here is probably not accurate). Here's an excerpt:

public class ProcessManager
{
    // create a new process to monitor the current process
    // passing in the current process id as args
    public void StartObserverProcess()
    {
        _mainProcess = Process.GetCurrentProcess();
        _mainProcessId = _mainProcess.Id;

        _observerProcess = new Process
        {
            StartInfo =
            {
                FileName = _mainProcess.MainModule.FileName,
                Arguments = _mainProcessId.ToString()
            },
            EnableRaisingEvents = true
        };
        _observerProcess.Exited += OnObserverProcessExit;
        _observerProcess.Start();
    }

    private void OnObserverProcessExit(object sender, EventArgs e)
    {
        // do something on main process exit
    }
}