Steps to reproduce:
1. Place a grid on a form and add several columns.
2. Set a ColumnGroupsViewDefinition to the grid and resize the columns so the horizontal scroll bar appears.
3. Add a button and on its click call the PrintPreview method of the grid.

You will see that the horizontal scroll bar of the grid will disappear.

Workaround:workaround it by increasing and decreasing the width of a single column with 1 pixel right after you call the Print method of the print document.

document.Print()
  grid.Columns(0).Width += 1
  grid.Columns(0).Width -= 1