I'm not sure if this would be considered a bug or not.
If you highlight a group of tracks and update using an action or the tag panel, you can still save the original values back over what was just updated.
Steps:
highlight all tracks in an album
execute an action (or use View, Tags) to remove the album name
with the tracks still highlighted (default), make a change using the tag panel to any field and save (or just save with no change)
Appears to be working, thanks for the quick response.
Your reference to 'Undo operations' reminded of another issue I just confirmed.
Execute an action (or group of) that takes more than a second.
When the 'Writing tag-data' dialog appears, click Cancel
The dialog will disappear, however the action continues and the dialog will reappear with the action executing against all selected tracks regardless of how many times you click Cancel
One note: After cancelling an Action that did execute against a few tracks that were selected Edit , Undo is greyed out and cannot be selected. It is available after an uninterrupted Action. Is this expected?
Are you sure that the file view is focused and not one of the fields in the tag panel? Edit > Undo has different behaviour dependent on which element from the GUI is focused.
I was cancelling the action before it actually was able to do anything; therefore there was nothing to cancel. I could have sworn that the status bar reported that a few tracks were updated.