Currently, the AutoCompleteBox's Tokens property is of type Collection<object>, this presents a problem when adding and removing items programmatically as there is no observability.

When an item is added or removed, the UI is not updated even though the token s collection has been. 

Here is a simple repro:

private void RadListView_OnItemTapped(object sender, ItemTapEventArgs e)
{
    // For this example e.Item is of type string

    (autoComplete.Tokens as Collection<object>)?.Add(e?.Item);

    // Item is added, but UI is not updated
    Debug.WriteLine($"Tokens count: {(autoComplete.Tokens as Collection<object>)?.Count}");
}