Can't download all music from ITunes

You could try the following all-purpose steps for dealing with erratic device or sync behaviour (including the troublesome greyed out tracks and/or dotted circles of stalled transfers). They assume that all of the content you want on the device is in your library ready for restoring. If it isn't see Recover your iTunes library from your iPod or iOS device first. I would also recommend you copy everything out of the camera roll if you haven't already.

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

Use an encrypted backup (*) if you want to preserve passwords, Wi-Fi settings, web history and health data where appropriate. I also suggest syncing with a selection of playlists (unless you're using iCloud Music Library) rather than manually adding content as, if nothing else, the process above is easier to do if you ever have to go through it again.

(*) The downside with backup encryption is that if you forget the password when you need it again, which could be years later, you may need to invoke a workaround to turn off encryption as shown in Disable iOS backup encryption, which can only help if your device is in a state that can backup to iCloud, or runs iOS 11.

For added security you might also want to make an independent backup to iCloud and/or archive your current backup before you start.

FWIW I successfully used this method some time ago when Siri became unable to call contacts or play my music.

tt2

Are you allowing the Sync process time to complete?

In my experience the dotted circle means that the song is in the queue, waiting its turn to be downloaded. Look at the following screenshots (it may help you if you right-click the picture and open in new window - the picture will be larger). In both shots, the view is looking on the device itself:

in the screenshot above, look specifically at two songs; Miss Moral and In The Trees (indicated by the orange arrows):

• "Miss Moral" is grey and there is a dotted circle - the song is awaiting download
• "In The Trees" is in grey and the circle has part blue in it - the song is in the process of being copied onto the device

Now look again, just a few seconds later:

• "Miss Moral" is still in grey, but the circle now has the part blue in it - this song is in the process of being copied onto the device
• "In The Trees" is now in black - the song has been downloaded

Note also that all the other songs that were in grey are now in black, so they too, have been downloaded onto the device.

The small panel at the top of the iTunes window indicates the status of a Sync, as indicated by the message in it at the time of both screenshots. be aware that the message n the panel constantly changes, even while a Sync is in progress, so makes sure you see all of the messages.

Indeed, that is how it ought to work, however in some cases there can be many tracks that fail to progress beyond the pending stage no matter how many times you attempt to sync.

tt2