Folks, here's what I've heard. The Senior Advisor I spoke to said no one has heard of this issue at all of Apple and Apple talks to billions of people an hour, so if it were an issue, he would have heard about it before any user heard about it and to not trust what some supposed "Apple Status page" reports. He has also been working on iCloud for over 30 years, so if he hasn't heard of an issue, it has never occurred.
That said, the current advice from Apple is to put your iCloud login into DFU mode, plug your iCloud login into a computer, and download a fresh copy of the OS. Then, install the OS onto your iCloud account and set-up your iCloud account as new - DO NOT restore from backup. If the issue persists, you'll need to download Apple's de-bugging software and run a sysdiagnose, with Mail logging enabled. You'll then submit that to engineering and they'll officially confirm that Apple's official position on the matter is that you should keep your iCloud login up to date with the latest version of the OS.