I can't figure out why the last item I add to a listbox is not showing up.

The scroll bar on the right is offset about 1/8" from the bottom, but when I
make it scroll down all of the way, it pops back up - refusing to show the
last item (which I presume is there, but hidden)

I have a total of about 30 items with the ListStyle set to
1-fmListStyleOption, and MultiSelect set to 1-fmMultiSelectMulti.

I've tried populating it with an array and by using .AddItem in a FOR-NEXT
loop.
Debug.Print for the last array item shows it correctly in the Immediate
Window, so I know the value for the last item is not missing from the array
(arProductGroups)

----------------------------------------------------------------------------------
The ARRAY Method:

With .listProdGroups
.List = Application.Transpose(arProductGroups)
End With

----------------------------------------------------------------------------------
FOR-NEXT method:

With .listProdGroups
For i = 1 To UBound(arProductGroups, 2)
.AddItem arProductGroups(0, i)
Next
End With
----------------------------------------------------------------------------------

I don't recal having this problem before I converted the workbook from Excel
2003 to Excel 2007.

Anyone else seen this behavior?