Upgrading to ASP.NET 4.5/MVC 4 forms authentication fails

I've just downoaded a VS 2012 along with ASP.NET 4.5 and MVC 4.0 and was kicking the tires with a sample app and found that the forms authentication that works perfectly with ASP.NET 4.0/MVC 3 no longer seems to work with the latest release.

When I make a call to the Login function in the action controller, the WebSecurity.Login call fails:

public ActionResult Login(LoginModel model, string returnUrl)
{
    if (ModelState.IsValid && WebSecurity.Login(model.UserName, model.Password, persistCookie: model.RememberMe))
    {
        return RedirectToLocal(returnUrl);
    }

    // If we got this far, something failed, redisplay form
    ModelState.AddModelError("", "The user name or password provided is incorrect.");
    return View(model);
}

I've replaced this code with the equivalent in my VS 2010 source, and that also fails (using the now deprecated FormsAuthentication.Authenticate function).

My question is: Has anybody ported a MVC3 to MVC4 app and found a workaround to this issue? I'm using IIS Express, so I guess that may be causing some problem somehow, but if you have any ideas, I'd appreciate it.

I copied my configuration from my working asp.net 4/MVC3 app as follows, but no luck (here's the relevant parts):

  <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=tcp:sql2k1201.dbprovider.net;Initial Catalog=SQL2012_db;User ID=SQL2012_db_user;Password=dbpassword;" providerName="System.Data.SqlClient" />
  </connectionStrings>

  <system.web>
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime targetFramework="4.5" />

    <authentication mode="Forms">
      <forms loginUrl="~/Account/Login" timeout="2880"/>
    </authentication>

    <membership>
      <providers>
        <clear/>
        <add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="DefaultConnection"
           enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false"
           maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
           applicationName="/" />
      </providers>
    </membership>

    <profile>
      <providers>
        <clear/>
        <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="DefaultConnection" applicationName="/" />
      </providers>
    </profile>

    <roleManager enabled="true">
      <providers>
        <clear/>
        <add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="DefaultConnection" applicationName="/" />
      </providers>
    </roleManager>