I thought with my earlier testing the code worked on both instances (which at that time were Sequence Table fields) but now I've retested it I can see it only caught the inline field. Now it appears that the first field is in a Shape object so the code would change to ...
Code:
Sub AppendixParensIntegrated2()
' Charles Kenyon and Andrew Lockton using code from Graham Mayor
' October 21, 2021
' https://www.msofficeforums.com/word/47835-putting-parentheses-around-sequence-number-caption-label.html
Dim oStory As Range, oFld As Field, iCount As Integer, aRng As Range, aShape As Shape
On Error Resume Next
For Each oStory In ActiveDocument.StoryRanges
For Each oFld In oStory.Fields
If oFld.Type = wdFieldSequence Then
If oFld.Code Like "*Appendix*" Then
oFld.Code.Text = "SEQ Appendix \# ""(#)"" "
iCount = iCount + 1
End If
End If
Next oFld
Next
For Each aShape In ActiveDocument.Shapes
If aShape.TextFrame.HasText Then
For Each oFld In aShape.TextFrame.TextRange.Fields
If oFld.Type = wdFieldSequence Then
If oFld.Code Like "*Appendix*" Then
oFld.Code.Text = "SEQ Appendix \# ""(#)"" "
iCount = iCount + 1
End If
End If
oFld.Update
Next oFld
End If
Next aShape
ActiveDocument.Fields.Update
Set oFld = Nothing
Set oStory = Nothing
On Error GoTo 0
MsgBox iCount & " instances bracketed.", vbOKOnly, "Macro complete"
End Sub