CollectionView using DataTemplate is not updating ReactiveContentView BindingContext or ViewModel - xamarin.forms

Question

I'm using ReactiveUI and trying to get a CollectionView to use a ReactiveContentPage as it's item template in code behind. This works okay until the ReactiveContentView is nested under another Element.
The problem I have is that after scrolling the collection view, the items get duplicated. After debugging, it would seem that the ReactiveContentView's BindingContext or ViewModel aren't updated.
The samples below have been simplified to highlight the issue:
This doesn't work:
public partial class SampleCollectionPage : ReactiveContentPage<SampleCollectionViewModel>
{
private void Build()
{
Content = new CollectionView
{
ItemTemplate = new DataTemplate(() =>
{
return new ContentView
{
Content = new ReactiveContentView<CollectionItemViewModel>
{
Content = new StackLayout
{
Children =
{
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.Title)),
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.Description)),
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.SomeTime)),
}
}
}
};
}),
}
.Bind(CollectionView.ItemsSourceProperty, path: nameof(SampleCollectionViewModel.Items));
}
}
This works:
public partial class SampleCollectionPage : ReactiveContentPage<SampleCollectionViewModel>
{
private void Build()
{
Content = new CollectionView
{
ItemTemplate = new DataTemplate(() =>
{
return new ReactiveContentView<CollectionItemViewModel>
{
Content = new StackLayout
{
Children =
{
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.Title)),
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.Description)),
new Label()
.Bind(Label.TextProperty, nameof(CollectionItemViewModel.SomeTime)),
}
}
};
}),
}
.Bind(CollectionView.ItemsSourceProperty, path: nameof(SampleCollectionViewModel.Items));
}
}
The only difference being that the working version doesn't put the ReactiveContentView in a ContentView. I'm not sure if I'm missing something or whether this is an bug in Xamarin Forms or ReactiveUI?
(edited to add actual problem: doh)