Setup: Windows 10 64-bit, iTunes 184.108.40.206, iPod Classic 160Gb. I have several gigabytes of music, podcasts and audiobooks in iTunes, all of which I have been syncing to the Classic for years, without problems.
I now have a new Touch 128Gb (iOS 10.3.1). I have tried several times to sync everything* to this device, but without success. iTunes shows that it is copying many items for a long time and then "finishes", but it seems that nothing or only a few gigabytes have been copied. If I try to sync again, I sometimes get an error message about failing to start the sync.
I am now updating the Touch to iOS 11 in the hopes that this will fix it.
What else could I try?
*I have selected to sync all music, all episodes of all podcasts and all audiobooks.