300: Engraving Rules dialog, Voices page - radio buttons do not work correctly

In Sibelius 2.1 on both Mac and Windows, the radio buttons for voice positioning rules on the Notes 2 page of the House Style > Engraving Rules dialog do not display correctly.

When you open the dialog, all the options will appear to be switched off. You can switch the desired options on, and they will take effect when you click OK to close the dialog, but the next time you open the dialog these options will appear to be unselected again.

This problem is fixed in the free Sibelius 2.11 update, which can be downloaded here.