To reproduce:

Add a RadPivotGrid and a few columns, select one column and show the PrintingDialog. Select "Print Selection Only", exception will occur.

Workaround:
Use the following print style -

public class MyPrintStyle : PivotGridPrintStyle
{
    private Func<Rectangle, SizeF> getScaleFactors;
    private Func<int, Rectangle, float, int> getStartColumn;
    private Func<int, Rectangle, float, int> getEndColumn;
    private Func<int, Rectangle, float, int> getStartRow;
    private Func<int, Rectangle, float, int> getEndRow;

    private List<AggregateDescriptionBase> aggregates;
    private List<int> columnWidths;
    private List<int> rowHeights;

    private Type baseType;
    private BindingFlags flags;

    public override void Initialize()
    {
        base.Initialize();

        this.baseType = typeof(PivotGridPrintStyle);
        this.flags = BindingFlags.NonPublic | BindingFlags.Instance;

        this.getScaleFactors = this.GetFuncFromParent<Rectangle, SizeF>("GetScaleFactors");
        this.getStartColumn = this.GetFuncFromParent<int, Rectangle, float, int>("GetStartColumn");
        this.getEndColumn = this.GetFuncFromParent<int, Rectangle, float, int>("GetEndColumn");
        this.getStartRow = this.GetFuncFromParent<int, Rectangle, float, int>("GetStartRow");
        this.getEndRow = this.GetFuncFromParent<int, Rectangle, float, int>("GetEndRow");

        this.aggregates = GetField<List<AggregateDescriptionBase>>("aggregates");
        this.columnWidths = GetField<List<int>>("columnWidths");
        this.rowHeights = GetField<List<int>>("rowHeights");

    }

    private T GetField<T>(string name)
    {
        return (T)this.baseType.GetField(name, flags).GetValue(this);
    }

    private Func<T, TResult> GetFuncFromParent<T, TResult>(string method)
    {
        MethodInfo getScaleFactor = baseType.GetMethod(method, flags);
        var func = (Func<T, TResult>)Delegate.CreateDelegate(typeof(Func<T, TResult>), this, getScaleFactor);
        return func;
    }

    private Func<T1, T2, T3, TResult> GetFuncFromParent<T1, T2, T3, TResult>(string method)
    {
        MethodInfo getScaleFactor = baseType.GetMethod(method, flags);
        var func = (Func<T1, T2, T3, TResult>)Delegate.CreateDelegate(typeof(Func<T1, T2, T3, TResult>), this, getScaleFactor);
        return func;
    }

    public override void DrawPage(Rectangle drawArea, Graphics graphics, int pageNumber)
    {
        int x = drawArea.X;
        int y = drawArea.Y;
        SizeF scale = this.getScaleFactors(drawArea);
        
        int startColumn = this.getStartColumn(pageNumber, drawArea, scale.Width);
        int endColumn = this.getEndColumn(startColumn, drawArea, scale.Width);
        int startRow = this.getStartRow(pageNumber, drawArea, scale.Height);
        int endRow = this.getEndRow(startRow, drawArea, scale.Height);
        int aggregateIndex = 0;
        for (int i = startRow; i <= endRow; i++)
        {
            x = drawArea.X;
            int maxHeight = 0;
        
            for (int j = startColumn; j <= endColumn; j++)
            {
                if (j == 0 && i == 0 && aggregateIndex < this.aggregates.Count)
                {
                    while (aggregateIndex < this.aggregates.Count)
                    {
                        if (j >= this.columnWidths.Count || i >= this.rowHeights.Count)
                        {
                            break;
                        }
        
                        Rectangle aggregateElementRect = new Rectangle(x, y, this.columnWidths[j], this.rowHeights[i]);
                        RadPrintElement aggregatePrintElement = this.GetAggregateDescriptorCell(aggregateIndex++);
                        aggregatePrintElement.ScaleTransform = scale;
                        RectangleF aggregateTransformedRect = aggregatePrintElement.GetTransformedBounds(aggregateElementRect);
                        this.PrintElement(aggregatePrintElement, drawArea, aggregateElementRect, graphics);
                        x += (int)Math.Floor(aggregateTransformedRect.Width);
                        maxHeight = Math.Max(maxHeight, (int)Math.Floor(aggregateTransformedRect.Height));
                        if (aggregateIndex < this.aggregates.Count)
                        {
                            j++;
                        }
                    }
        
                    continue;
                }
        
                Rectangle elementRect = new Rectangle(x, y, this.columnWidths[j], this.rowHeights[i]);
                RadPrintElement printElement = this.GetPrintElementForCell(i, j);
                printElement.ScaleTransform = scale;
                RectangleF transformedRect = printElement.GetTransformedBounds(elementRect);
        
                this.PrintElement(printElement, drawArea, elementRect, graphics);
                x += (int)Math.Floor(transformedRect.Width);
                maxHeight = Math.Max(maxHeight, (int)Math.Floor(transformedRect.Height));
            }
        
            y += maxHeight;
        }
    }
}