Facing the same problem I found the quickest solution was to actually scan the rows of the cells I wished to sort, determine the last row with a non-blank element and then select and sort on that grouping.
Dim lastrow As Integer
lastrow = 0
For r = 3 To 120
If Cells(r, 2) = "" Then
Dim rng As Range
Set rng = Range(Cells(3, 2), Cells(r - 1, 2 + 6))
rng.Select
rng.Sort Key1:=Range("h3"), order1:=xlDescending, Header:=xlGuess, DataOption1:=xlSortNormal
r = 205
End If
Next r