Nullable param in asmx service method causes other method to fail

To recreate the issue I'm seeing, using VS2010, create an empty website and add a web service (asmx) with code-behind.

Using the following code, both webmethods can be invoked successfully:

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class WebService : System.Web.Services.WebService {
    [WebMethod]
    public void Method1(int x) {
        // i'm good
    }
    [WebMethod]
    public string Method2(int x) {
        return "it worked";
    }
}

Now, if I change the parm on method 2 to a nullable type it works just fine, but it will make method 1 fail...

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class WebService : System.Web.Services.WebService {
    [WebMethod]
    public void Method1(int x) {
        // no changes made to this method, but it no longer works
    }
    [WebMethod]
    public string Method2(int? x) {
        return "it worked";
    }
}

The resulting error is one that I've seen before if a param is missing when calling a service:

System.IndexOutOfRangeException: Index was outside the bounds of the array. at System.Web.Services.Protocols.HttpServerType..ctor(Type type) at System.Web.Services.Protocols.HttpServerProtocol.Initialize() at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing)

Also, this only appears to break if the first method returns void, so this also works fine:

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class WebService : System.Web.Services.WebService {
    [WebMethod]
    public string Method1(int x) {
        return "works again";
    }
    [WebMeth