I have a .NET MVC RESTful API that works fine for GET and POST, but returns 404 for PUT requests:
[Authorize]
public class TasksController : ApiController
{
    // GET api/tasks
    /// <summary>
    /// Get all users tasks.
    /// </summary>
    /// <returns>Task Object (JSON serialised)</returns>
    public IEnumerable<Task> Get()
    {
        List<Task> tasks = new List<Task>();
        ...
        return tasks;
    }
    // GET api/tasks/5
    public Task Get(Int64 id)
    {
        Task thisTask = new Task();
        ...
        return thisTask;
    }
    // POST api/tasks
    public void Post(Task item)
    {
        if (item == null)
        {
            throw new ArgumentNullException("item");
        }
        ...
    }
    // PUT api/tasks/5
    public void Put(Int64 id, Task item)
    {
        if (item == null)
        {
            throw new ArgumentNullException("item");
        } 
        ...
    }
    // DELETE api/tasks/5
    public void Delete(int id)
    {
        ...
    }
    // PUT, GET, POST, DELETE api/tasks...
    [AllowAnonymous]
    public HttpResponseMessage Options()
    {
        var response = new HttpResponseMessage();
        response.StatusCode = HttpStatusCode.OK;
        return response;
    }
}
Any idea why it wouldn't be picking up the PUT? (Even OPTIONS works fine)
Routing:
    public static void Register(HttpConfiguration config)
    {
        // Web API configuration and services
        // Configure Web API to use only bearer token authentication.
        config.SuppressDefaultHostAuthentication();
        config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));
        // Web API routes
        config.MapHttpAttributeRoutes();
        // CORS Enabled
        //var cors = new EnableCorsAttribute("localhost", "*", "*");
        //config.EnableCors(cors);
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
        var appXmlType = config.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(t => t.MediaType == "application/xml");
        config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType);
    }
}
Web.Config:
<httpProtocol>
  <customHeaders>
    <add name="Access-Control-Allow-Origin" value="*" />
    <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
    <add name="Access-Control-Allow-Headers" value="Authorization, Content-Type" />
  </customHeaders>
</httpProtocol>
Addendum It looks like the speed at which it is coming back is instant, even after a recompile, So I'm guessing it's not even getting to the application, so must be a configuration issue.
