How to Detect System Shutdown in WPF App's OnExit Method?

Question

I'm working on a WPF application and facing a challenge with detecting a system shutdown in the OnExit method. The goal is to send different Mixpanel events based on whether the application is closing due to a user action or a system shutdown.

Here's the relevant part of my App.xaml.cs:

protected override void OnExit(ExitEventArgs e)
{
    if (_mutex != null)
    {
        _mutex.ReleaseMutex();
    }
    if (EventListenerHelper.IsSystemShuttingDown)
    {
        // Send PC_SHUTDOWN event if the system is shutting down
        MixpanelService.AddEventInMixpanel(EventsNames.PC_SHUTDOWN, "PC is shutting down");
    }
    else
    {
        // Send CLOSE_CHROMAX event for regular application exit
        MixpanelService.AddEventInMixpanel(EventsNames.CLOSE_CHROMAX, $"Close Chromax WPF Application with Exit Code: {e.ApplicationExitCode}");
    }
    base.OnExit(e);
}

And in EventListenerHelper.cs, I have:

public static class EventListenerHelper
{
    public static bool IsSystemShuttingDown { get; private set; } = false;

    // ... Other methods ...

    private static void SystemEvents_SessionEnding(object sender, SessionEndingEventArgs e)
    {
        if (e.Reason == SessionEndReasons.SystemShutdown)
        {
            IsSystemShuttingDown = true;
        }
    }
}

I expected IsSystemShuttingDown to be true during a system shutdown, but it seems like it's not working as expected. The OnExit method doesn't seem to correctly identify the shutdown scenario.

Is there a better or more reliable way to detect a system shutdown in the OnExit method of a WPF application? Am I missing something in how I'm setting or checking the IsSystemShuttingDown flag? Any insights or alternative approaches to achieve this would be greatly appreciated. Thanks in advance!