format of date after array resort - one date refuses to play ball

Hi
The following code lifts data from a sheet and via an array resorts copies it back the same sheet. The date is in the correct format "11/07/19" before macro is run

with ws1  
 MyArr = .Range("a1:h" & Lrow).Value
   .UsedRange.ClearContents
   .Columns(3).NumberFormat = "dd/mm/yy"
   For i = 1 To 6
      Cells(1, i).Resize(UBound(MyArr)).Value = Application.Index(MyArr, 0, Choose(i, 1, 6, 5, 3, 4, 7))
  Next i
End With

The dates are returned to column 3 and even though the column is formatted to date and the code specifies the date format our friend above resolutely returns as "07/11/19"

No other dates seem affected

Any ideas