Using the GUI to set the vertical justification (for some reason referred to as "vertical orientation" in the documentation) to "Top" sets the VertOrient value to zero (described as "None") rather than 1 (described as "Top". The documentation is sdk/docs/common/ref/com/sun/star/text/VertOrientation.html (in whatever directory you have)

To reproduce - create a document with a text table. Use the GUI to set the vertical justification of the top left cell to the top. Run the macro below, and the value will be zero.

Setting it to the centre or bottom give the values 2 & 3 respectively as expected.

REM  *****  BASIC  *****
option explicit

Sub Main
dim DocEnum as Object
dim DocElement as Object

  DocEnum=ThisComponent.text.createEnumeration
     
  do while DocEnum.HasMoreElements 
    DocElement=DocEnum.NextElement
    if DocElement.SupportsService("com.sun.star.text.TextTable") Then
      msgbox ("VertOrient= " & DocElement.GetCellByPosition(0,0).VertOrient)
    end if
  loop

End Sub