Manually managing music has stopped working altogether

Jawgust

I am having the same issue like you ... I too manually manage my music but when i got the 128 GB iPhone 6 the plan was to sync my whole library.... work for awhile until i updated iTunes and to windows 10....Now i have to go back manually managing....iTunes keeps update same files on the iPhone every time i plug it in the computer and it like a gamble because sometime it update the song and video without any problem and the other time (more like 80%) it would get stuck in the process and the item on the iPhone will lose the albums cover and some also become unplayable...

These steps should work:

1. Backup device.
2. Restore as a new device.
3. Restore the backup made earlier.

Note backing up no longer transfers purchased apps from your device into iTunes. Make sure you have up-to-date copies of all your apps in your iTunes library before restoring or you may loose settings and data associated with apps that are not in your library when you restore.

Syncing with selected playlists makes the process of restoring a backup easier than it is with manually management. You should have just as much control, indeed more since you can edit the playlists when your device isn't connected, and you get syncing of ratings, playcounts, etc.

tt2

The standard troubleshooting approach with an Apple device that isn't working as expected is to make sure that iTunes is fully up to date and to restore the device. In the case of iOS devices you should backup your information beforehand and restore afterwards. Is that guaranteed to work? Not always. Is there a way to ensure it doesn't go wrong again? I doubt it. It does seem perhaps that iTunes has problems when a large quantity of media is queued up for transfer, and if something goes wrong it doesn't recover gracefully. If it were in my power I would work on that issue, but I'm just another user so all I can offer is my advice. In practice, and despite your preference for manual management, I would nonetheless recommend syncing with selected playlists. This is a technique I used to use on my 160Gb classic for repopulating it.

Break up large transfers

Once you've restored your iPod don't rush to dump all the data back exactly as it was before. I have found that lots of large or complex smart playlists can sometimes trigger constant reboots or dumping of the iPod's library. In addition, larger transfers can fail leaving data in an inconsistent state. Try this technique for populating the iPod in stages.

In iTunes select the menu item File... New Smart Playlist. Change the first drop-down box to Playlist, the next to is and the next to Music or whatever playlist holds the bulk of the content you want on your device. Tick against Limit to, type in say 10, then change the drop-down to GB, and set the last drop-down to artist. When you click OK you can enter a name for the playlist, e.g. Transfer.

Now sync this playlist to your iPod rather than your entire library. When the sync is complete modify the rule (File... Edit playlist) to increase the size by your chosen amount, then sync and repeat. You can experiment with different size increments, if it doesn't work just choose something a bit smaller until it works each time. Before long you should have all your music on your iPod. Once that's done you can move on to other media such as podcasts, videos, photos, playlists, etc.

Syncing to one or more playlists should give you more control, rather than less, since you can update the selection whether the device is connected or not, and it should simplify the process of restoring your device as and when that should become necessary again.

tt2