The address book group in question contains a group plus some individual contacts.
If I use the Import button, only the individual contacts are added to the recipients list. I have to explicitly Import the sub group to get those contacts added as well.
Drag/drop of the group doesn't work at all.
If I select the contents of the group (i.e. the sub group & the individual contacts) & then drag/drop - only the individual contacts are added. Drag/drop of the sub group does nothing.
And oddly enough if I then select the contents of the sub group (or any other contact/contacts for that matter) and then drag/drop, they are not added either.
It seems that there's a general problem with drag/drop from address book:
1) Drag/drop of a group doesn't work at all.
2) Subsequent drag/drop of any contacts after the initial recipient list drag/drop, fails to add to them to the list.