Syncing music files from macbook to iphone only transfers a few tracks

See If you have music that won't play on your device - Apple Community. Your iCloud capacity should have no impact on media syncing. Are all the songs you are trying to sync on your computer? Or have you somehow placed some of these in the cloud using iCloud Drive or a similar service? Have you previously subscribed to either Apple Music or iTunes Match? The cloud with a cross looks like something you would only see if Sync Library was enabled on the device.

tt2

arno_t wrote:

Old playlists are still all there, in the same half synced, half broken state. Can't seem to get rid of these, they were synced to this iPhone with a previous laptop though, is this the problem?

Possibly. Make sure on the phone that you no longer have Sync Library enabled. See Use Sync Library with your Apple Music subscription - Apple Support if needed. Then you should probably clean all the tracks off the device in the way outlined in my earlier post, then check that the playlists have also been removed. Again it may be possible to delete those directly on the device. IIRC manually deleting content from a device via Finder isn't trivial. Once all has been removed from the device you should be able to sync selected content from the local library.

tt2

Yes, it should disappear once your subscription lapses. I was just making sure. The cloud with an x is used to denote iCloud Music Library tracks that have been removed, so I don't know why you're seeing those on the device with no active subscription and sync library turned off. If you haven't done it recently a reboot might be in order.

tt2

Again, possibly. iPhone is designed to sync with a single library. If you transfer the library correctly from one computer to another it appears to be the same library and things carry on as normal. Your "loco" library may somehow have inherited the old identifier. What normally happens with a new library is that you get an erase and sync warning when you attempt to sync, and if you proceed all content on the device is removed before new content is added.

tt2

When you're signed into your Apple Account you should get download links for any unhidden purchases not currently downloaded to the device. If you see any other links that seems like cruft from the previous subscription. You may have to take the deeper cleaning advice I gave in the first link. Backup device, restore as a new device, restore backup, sync media. Recommend backing up to both computer and iCloud before you go down this route.

tt2