I am attempting to have some code executed whenever any row in column
"S" contains the letter "B". In other words, I would like the code to
run whenever the user enters a "B" in any row in column "S".

Nothing is happening when I enter a "B" in a random row in column "S"
to the best of my knowledge.

Promise, I have not exited the "Design Mode". Besides, my other macros
are running fine.

Note: I also attempted using worksheet_change event (nothing happened
still). A couple variations in code I have tried are below.
-----------------------------------------------------------------------------------
Private Sub Workbook_Change(ByVal Target As Range)

If Target.Column < 19 Then Exit Sub
If Cells(Target.Row, Target.Column).Value = "B" Then
MsgBox "It works...Not"
End If

End Sub
-----------------------------------------------------------------------------------
Also tried this among many other variations...
-----------------------------------------------------------------------------------
Private Sub Workbook_Change(ByVal Target As Range)

If Target.Column = 19 Then
If Cells(Target.Row, Target.Column).Value = "B" Then
MsgBox "It works...JK"
Else
Exit Sub
End If
End If

End Sub
-----------------------------------------------------------------------------------

Thoughts as to why the code doesn't seem to be doing anything?