As the customer indicates, in `TSeriesPointer.DrawPointer`, when using  `psSmallDot`, we call `Pixels[PX,PY]`, but it doesn't draw any point in the chart.

Find below a simple example to reproduce the problem:

uses Chart, Engine, Series;

var Chart1: TChart;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Chart1:=TChart.Create(Self);

  with Chart1 do
  begin
    Parent:=Self;
    Align:=TAlignLayout.Client;
    Color:=TAlphaColors.White;
    Gradient.Visible:=False;
    Walls.Back.Color:=TAlphaColors.White;
    Walls.Back.Gradient.Visible:=False;
    Legend.Hide;
    View3D:=False;
  end;

  with TPointSeries(Chart1.AddSeries(TPointSeries)) do
  begin
    Pointer.Style:=psSmallDot;
    FillSampleValues;
  end;

  //Chart1.Canvas.UseBuffer:=True; // doesn't work either
end;