Grouping fixed

gistfile1.txt

using DynamicData;
using DynamicData.Binding;
using ReactiveUI;
using ReactiveUI_GroupingIssueTest_Wpf.Enums;
using ReactiveUI_GroupingIssueTest_Wpf.Models;
using System;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reactive.Linq;

namespace ReactiveUI_GroupingIssueTest_Wpf.ViewModels
{
    public class TestViewModel : ReactiveObject
    {
        private readonly Random rnd;
        private readonly SourceCache<Male, int> cache;

        private readonly ReadOnlyObservableCollection<GroupTansformed> maleGroups;
        public ReadOnlyObservableCollection<GroupTansformed> MaleGroups => maleGroups;
        

        public TestViewModel()
        {
            rnd = new Random();
            cache = new SourceCache<Male, int>(male=> male.Id);
            cache.AddOrUpdate(Enumerable.Range(1, 11).Select(i => new Male(i, Greek.Alpha)));

            cache.Connect()
                .AutoRefresh(male => male.FavouriteGreekLetter)
                .Group(male => male.FavouriteGreekLetter)
                .Transform(group => new GroupTansformed(group))
                .ObserveOn(RxApp.MainThreadScheduler)
                .Bind(out maleGroups)
                .DisposeMany() // When a group is deleted we need to dispose it
                .Subscribe();


            Observable.Interval(TimeSpan.FromSeconds(1))
                .Select(s => cache.Items.Skip(rnd.Next(0, cache.Count)).FirstOrDefault())
                .WhereNotNull()
                .Do(male => male.FavouriteGreekLetter = Enum.GetValues(typeof(Greek)).OfType<Greek>().OrderBy(e => Guid.NewGuid()).FirstOrDefault())
                .Subscribe();
        }
    }

    public class GroupTansformed : AbstractNotifyPropertyChanged
    {
        private readonly IDisposable _cleanUp;

        public Greek Key { get; }

        private int _count;
        public int Count
        {
            get => _count;
            set => SetAndRaise(ref _count, value);
        }

        public GroupTansformed(IGroup<Male, int, Greek> group)
        {
            Key = group.Key;

            //Need to raise a notify property changed event for the count property.
            //NB: Also change binding to   <TextBlock Text="{Binding Count}" />
            _cleanUp = group.Cache.CountChanged.Subscribe(c => Count = c);        }

        public void Dispose()
        {
            _cleanUp.Dispose();
        }
    }

}