Not all music syncing from 5c to newest itunes

[bsbfan]

I am helping someone out who just upgraded from a 5c to an 8. They never backed up their 5 on their current computer so I did that but only like 50% of their music synced to itunes and then went to the new one when I synced. I have tried to sync over and over and I am getting no error message but still half the music on the 5c isn't on Itunes after I sync. What do I do?

 

[chscag]

Use a third party application: I use iMazing 2 which will do the job.