ReactiveSystem.cs

// Works
protected override Collector<GameEntity> GetTrigger(IContext<GameEntity> context)
{
  return new Collector<GameEntity>(
    new []
    {
      context.GetGroup(GameMatcher.Machine),
      context.GetGroup(GameMatcher.JustRepaired)
    },
    new []
    {
      GroupEvent.Added,
      GroupEvent.Added
    });
}

// Doesn't

protected override Collector<GameEntity> GetTrigger(IContext<GameEntity> context)
{
  return context.CreateCollector(Matcher<GameEntity>.AnyOf(GameMatcher.Machine, GameMatcher.JustRepaired));
}