|re: "The VB code itself appeared unchanged after formatting changes."|
I'm not surprised that the code wasn't changed since you can't edit a macro in that manner.
The only way a macro can be edited is by manually typing code into the VBA editor.
You can't even edit an existing macro with the VBA recorder since the recorder won't accept an existing macro name without asking the user if (s)he wants to replace it.
Again, the only thing that I can think of is that events are somehow being disabled by your actions.
One way to check that would be to put this code in the same sheet module and then, when the Copy/Paste code doesn't appear to work, enter a value in A1. If the message doesn't pop up, then events are disabled.
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$1" Then _
MsgBox "Events are Enabled"
A learning moment:
Note that the Copy/Paste macro is named:
while the one in this post is named:
The key is that the SelectionChange code fires as soon as a range is selected while the Change code fires after a range is changed.
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