[HTC Rezound] xv-6800:
OK, finally some resolution.

After more experimenting, it appears HTC Sync only knows to look in the default Windows location on the C: drive for playlists, while I keep mine on my D: drive.

For anyone else watching this thread and having problems, who keeps their playlists somewhere other than in the standard Windows location on C:, you must open your playlist, then save it to the My Music\Playlists folder on C:. WMP will automatically insert hard paths to the songs in the list.

Also, playlists must be in .WPL format. You should also NOT select to sync a specific music folder within the HTC Sync interface. Let HTC Sync manage your music via Playlists (if you indeed do want to manage playlists on your computer), because it will also sync the music in the playlists, and place the songs in relative locations to the playlists. If you also have HTC Sync set to sync a specific music folder, you will end up with dupes and waste space. Ask me how I know!

After syncing, your .WPL files will be converted to .M3U on the phone (your PC files will be untouched), and will contain hard paths to the files on the phone. Leave these alone. While you can edit the playlists within the music app, do not try to manually edit the .M3U files themselves, because they will magically then disappear from the Playlist list in the music app, and from the storage on the phone, too. Don't ask!

Then, before disconnecting the phone, you must disable syncing of Music, otherwise, everytime you connect your phone, the music app will make duplicate playlists on the phone. Note that these duplicates are not true duplicates for the playlist files on the storage, they just look like they are; in other words, each duplicate of a playlist is linked to its one counterpart playlist file on the storage. If you delete any of them, you will end up deleting the actual playlist file, so the next time the music app reads from the card, like after the next time you connect to the computer and either sync, or use the phone as a disk drive the respective playlist will disappear altogether (although the music itself will stay). So, the best way to get rid of dupes is to Clear Media Storage, then unmount and remount the card.

Any time you want to add playlists, you must connect the phone, let it sync, and without exiting HTC Sync, enable music syncing, unselect all playlists and sync again. This, of course, will delete all playlists and the music referenced within the lists, from the phone. Exit and restart HTC Sync, so it will see your new playlist and display it in the Playlists section in HTC Sync. Select all the playlists you want to send to your phone and it will send them all. In effect, you're not really syncing as far as true sync is concerned, you're really sending everything again.

Oh, wait there is yet one more caveat. If there is one error in any of your playlists, such as pointing to a song that you deleted, or something, ALL your playlists WILL be deleted, because it appears the phone's internal playlist database can't handle errors in playlists.

It's a very terrible way to do things, but at least it's POSSIBLE to get playlists sent to the phone.... BARELY!

Oh, BTW, I contacted HTC. They sent me some new unreleased revs of the HTC Sync software. The revs did not help, but I left them installed anyway.