Can't get music transferred to iPhone 6

iTunes will not copy my music library to my iPhone 6. I have plenty of space on the phone for the entire library and I have "Sync Music" and "Entire Music library" checked in iTunes, but when I sync it never actually copies the music over. It did not load the music on the phone when I first set it up as a restore from my old iPhone backup.

I have restarted both the phone and my iMac and tried toggling the setting for syncing only checked music in iTunes. Nothing works.

Before sync, the Summary tab for my phone in iTunes shows that there will be 17GB remaining after the music sync, but as it goes through the sync, it skips over the music transfer step, then spends a long time waiting on the last step (something about waiting for changes to take place... don't remember exactly what iTunes says). Once the sync is finished it shows that 42 GB are still free on the phone and the blue bar for music is gone, and nothing has been transferred to the phone.

I have tried syncing only playlists with smaller numbers of files and get the same result.

I have never been shown any kind of error message.

I have the phone connected to the iMac using the cable that came with the phone.

I am using the most up to date version of Mavericks and iTunes on a 2009 iMac and I have a 64GB iPhone6.