Users of iTunes 8.1 have reported issues when syncing some first- and second-generation iPod shuffle units.
According to an Apple Discussions thread, iTunes 8.1 creates duplicate files on these shuffles when dragging files to the iPod that already exist on the device, does not place podcasts at the beginning of the play order on the shuffle, sorts alphabetically rather than by date, doesn’t automatically delete podcasts on the shuffle that have been deleted from the Podcasts list in iTunes, and doesn’t allow users to play songs from the shuffle in iTunes when the device is connected.
The problems appear to be occurring on both Mac and PC computers; some users have reported that restoring the shuffle fixes all problems, while other users have had only limited success following a restore.