AngularJS select doesn't honour selected value - asp.net-mvc

Question

I have an ASP.NET MVC controller with a VideModel I serialize into JSON and send to the client, along with a view and marry those two together using AngularJS. The view model has a lookup (array) that is bound to a Select element. It all works fine and I can select a value, post the form back to the MVC controller and get the selected value there.
When I send back a view model with a value already selected, the value is not selected in the Select element. I can see that the value is correctly set on the client side (using Batarang) but the Select still doesn't show that as selected. Here's a link to the sample showing this. Any ideas?
Here's the code snippets to give you some ideas (angular controller doesn't have any code, just a mean to add new item with default values to the destination array).
MVC Controller:
public Sources {
First,
Second,
Third
}
public ActionResult MyGetAction()
{
var vm = new MyViewModel {
Sources = SelectListExtension.ToSelectListItem<Sources>() //Would return IEnumerable<SelectListItem> (with proper Value and Text for all enum entries)
Destination = new List<DestinationViewModel>(); //Has int? SourceId
};
vm.ClientData = SerializeToJson(vm);
return View(vm);
}
[HttpPost]
public ActionResult MyPostAction(MyViewModel model)
{
var selectedSource = model.Destination[0].SourceId; //works fine
model.Sources = SelectListExtension.ToSelectListItem<Sources>(); //populate the lookup again
//model still has 1 destination with the SourceId correctly set
return View(model);
}
My View bound to the JSON object:
#using (Html.BeginForm())
{
<div ng-repeat="destination in Destinations">
<select ng-init="destination.Source = { Value: destination.SourceId }"
ng-model="destination.Source"
ng-options="s.Text for s in Source track by s.Value"
ng-change="destination.SourceId = destination.Source.Value"
name="Destinations[{{$index}}].SourceId"
id="Destinations_{{$index}}__SourceId">
<option value=""></option>
</select>
</div>
<input type="submit">
}