iTunes Not Syncing Custom Ringtones
I'm having a problem where iTunes is not syncing my custom ringtones to my iPhone 6S (running 11.3.1). With iTunes 12.7.4.76 on macOS 10.13.4 and iTunes 12.7.4.83 on Windows 10 10.0.17134 Build 17134 I can drag and drop my m4r files onto the phone but it's stuck greyed out with a dashed circle next to it as shown in the screenshot.
Has anyone else been unable to sync their custom ringtones to their phone? The ringtones work on another iPhone I have for work and my iPad.
iPhone 6s, iOS 11.3.1