iPhone 6s handsets, many users are reporting now. Upon trying to restore their accounts and all the backed info onto the new replacement, they are increasingly finding out that some messages, call logs, and even Safari history and health stats, have simply disappeared.It's exactly these general backups that are going rogue after grabbing replacement
Some are attributing the bug to the fact that most users that have iPhone 6s on iOS 9.1 are getting replacements on iOS 9.0, while others are certain that the backups themselves have been corrupted for some reason. If you don't want to go through the trouble of updating to iOS 9.1 on both handsets, and then resetting the replacement to factory, you can simply back up via iTunes, or use third-party apps as an extra precaution. Apple is apparently aware of the issue, too, and working on a fix.