I have the new Oreo update for my S8, and aside from being really unhappy that the individualized text tone per contact feature was removed, I now can no longer change the text tone itself. I have tried changing it 3 times, even rebooted the phone, and while the notification tone name is listed as one thing, the tone sound itself is completely different than what is set.
I don't know what more to do, but I guess this is another failed issue with the new update.
I don't know what more to do, but I guess this is another failed issue with the new update.