This change was taken out by design. The fact that string label positions (and not value label positions) are changed should not necessarily change the positions of the values. The recommended way of working is this:

    Radar line;
    private void InitializeChart()
    {
      tChart1.Aspect.View3D = false;
      line = new Radar(tChart1.Chart);

      int length = 10;
      line.CircleLabels = true;


      for (int i = 1; i <= length; i++)
      {
        double angle = (360 / length) * i;
        line.Add(angle, angle, angle.ToString());
      }
    }

    private void button4_Click(object sender, EventArgs e)
    {
      line.ClockWiseLabels = !line.ClockWiseLabels;

      line.XValues.Order = line.ClockWiseLabels ? ValueListOrder.Descending : ValueListOrder.Ascending;
      line.XValues.Sort();
    }