Our app has dozens, perhaps hundreds, of PopupLists (app is C++/MFC). I am able to Select items from most of these lists, but I have a few where the Select fails. The developers claim these few are identical to all the others, not subclassed, not handled any differently. OK, fine, then why does SilkTest fail when selecting? They fail on selecting via index number, and they fail when selecting on a string. For what it's worth, these PopupLists work fine under CompuWare's TestPartner.
You did not post what the error was like while trying to select. Does it say "item not found" or is it the usual "control not responding" error.
Did you try recording the select action?
I know this is not a good solution (even I hate using this workaround): If the getcontents works for the popuplists, you could find the Index of the item from the list and do TypeKeys to select the item.