Why is the logon page is being displayed after seeding a database?

Question

I am coding a MVC 5 internet application, and have a question about being redirected to a logon page after seeding a database.

Here is my controller code:

public class SetupController : Controller
{
    [AllowAnonymous]
    public async Task<ActionResult> SetupApplication()
    {
        Database.SetInitializer<ApplicationDbContext>(new ApplicationDbInitializer());
        ApplicationDbContext applicationDbContext = new ApplicationDbContext();
        applicationDbContext.Database.Initialize(true);
        return RedirectToAction("Index", "Home");
    }
}

In the seed method, I am adding some objects to a different DbContext class, and for some reason, the logon page is being displayed afterwards. The ApplicationDbContext is for the IdentityStore. If I do not add any objects to the different DbContext class, the logon page is not shown.

When the logon page is displayed, the following exception is logged:

System.InvalidOperationException: An asynchronous module or handler completed while an asynchronous operation was still pending.

The exception occurs at:

Account\Login

If I comment out all of the code in the above method, except the RedirectToAction, the Index ActionResult is executed, and I am not required to logon. So I can browse to the Index ActionResult and I do not need to enter in any logon information. The exception does not occur with the code commented out.

Here is the Index ActionResult:

[AllowAnonymous]
public async Task<ActionResult> Index()
{
    return View();
}

Why would be the reason for this? What coding concept is occuring here? I do not believe I need to show code, but if needed, I will.

Thanks in advance.