I mainly use the USB connection between my MBA and iPhone 5s just to do backups. There is no music on my iPhone. Today, when I have connected my iPhone I have noticed a random music library from the person I have never met.
- macOS Sierra 10.12.4
- iOS 10.13.2
I can confirm that my iPhone has never been associated with another AppleID as I have bought it brand new.
Any ideas on what might be happening?