I have retested this here with a default grid on the form and the code:
procedure TForm4.FormCreate(Sender: TObject);
begin
advstringgrid1.FixedRows := 2;
advstringgrid1.FilterEdit.Enabled := true;
advstringgrid1.FilterEdit.Row := 1;
advstringgrid1.SaveFixedCells := false;
advstringgrid1.LoadFromCSV('c:\tmssoftware\cars.csv');
advstringgrid1.Cells[1,0] := 'Brand';
advstringgrid1.Cells[2,0] := 'Type';
advstringgrid1.Cells[3,0] := 'CC';
advstringgrid1.Cells[4,0] := 'Pk';
advstringgrid1.Cells[5,0] := 'Cyl';
advstringgrid1.Cells[6,0] := 'Kw';
advstringgrid1.Cells[7,0] := 'Price';
advstringgrid1.Cells[8,0] := 'Country';
advstringgrid1.HideColumn(advstringgrid1.ColumnByHeader('Country'));
advstringgrid1.HideColumn(advstringgrid1.ColumnByHeader('Price'));
end;
but I could not reproduce this issue here. Correct columns are hidden, grid has no AV on exit.
What are you doing different?