Consider this code (type names genericised for the purposes of example):

// Bound to ListBox.ItemsSource
_items = new ObservableCollection<Item>();

// ...Items are added here ...

// Specify custom IComparer for this collection view
_itemsView = CollectionViewSource.GetDefaultView(_items)
((ListCollectionView)_itemsView).CustomSort = new ItemComparer();

When I set CustomSort, the collection is sorted as I expect.

However I require the data to re-sort itself at runtime in response to the changing of the properties on Item. The Item class derives from INotifyPropertyChanged and I know that the property fires correctly as my data template updates the values on screen, only the sorting logic is not being called.

I have also tried raising INotifyPropertyChanged.PropertyChanged passing an empty string, to see if a generic notification would cause the sorting to be initiated. No bananas.

EDIT In response to Kent's suggestion I thought I'd point out that sorting the items using this has the same result, namely that the collection sorts once but does not re-sort as the data changes:

_itemsView.SortDescriptions.Add(
    new SortDescription("PropertyName", ListSortDirection.Ascending));