To reproduce:

ColumnGroupsViewDefinition columnGroupsView;
 
columnGroupsView = new ColumnGroupsViewDefinition();
columnGroupsView.ColumnGroups.Add(new GridViewColumnGroup());
columnGroupsView.ColumnGroups.Add(new GridViewColumnGroup());
columnGroupsView.ColumnGroups.Add(new GridViewColumnGroup());
columnGroupsView.ColumnGroups.Add(new GridViewColumnGroup());

columnGroupsView.ColumnGroups[0].Rows.Add(new GridViewColumnGroupRow());
columnGroupsView.ColumnGroups[0].Rows[0].ColumnNames.Add("colPINNED_LEFT");

columnGroupsView.ColumnGroups[1].Rows.Add(new GridViewColumnGroupRow());
columnGroupsView.ColumnGroups[1].Rows[0].ColumnNames.Add("colDATE");
columnGroupsView.ColumnGroups[2].Rows.Add(new GridViewColumnGroupRow());
columnGroupsView.ColumnGroups[2].Rows.Add(new GridViewColumnGroupRow());
columnGroupsView.ColumnGroups[2].Rows[0].ColumnNames.Add("colTITLE");
columnGroupsView.ColumnGroups[2].Rows[1].ColumnNames.Add("colTEXT");

columnGroupsView.ColumnGroups[3].Rows.Add(new GridViewColumnGroupRow()); 

columnGroupsView.ColumnGroups[3].Rows[0].ColumnNames.Add("colPINNED_RIGHT");

this.radGridView1.ViewDefinition = columnGroupsView;

this.radGridView1.Columns["colDATE"].Width = 110;
this.radGridView1.Columns["colTITLE"].Width = this.radGridView1.Width - 181;

this.radGridView1.TableElement.ViewElement.RowLayout.InvalidateRenderColumns();

columnGroupsView.ColumnGroups[0].PinPosition = PinnedColumnPosition.Left;  
columnGroupsView.ColumnGroups[3].PinPosition = PinnedColumnPosition.Right;