I don't know if this is an issue with the iPhone X, iOS, iTunes, or a combination. My ringtones did not carry over from 'restore from backup' to my new phone. I was able to add them later in the tones selection under the device in iTunes. However, when I decided to remove a ringtone from that same selection, it was removed from iTunes, but not from the phone (though it asked "Are you sure you want to remove the selected item from your iPhone?") even after a new sync. If I add a new tone in iTunes, it adds it to the phone and removes all previous custom tones from the phone, but stills shows them as being on the phone in iTunes.