https://www.cnet.com/news/apple-iphone-x-software-update-11-1-1-fixes-ios-11-autocorrect-bug/

You'll now be able to talk about yourself as much as you want in iMessages. 

A bug in Apple's iOS 11.1 software prevented some users from typing the letter "i." Instead, it would autocorrect to the letter "A" and a unicode symbol.