Another iOS 11 autocorrect bug affects the words "it" and "is"
Now, another autocorrect bug is afflicting iOS 11 users. Type the word "it" on your iOS 11 powered Apple mobile device and the word is automatically corrected to "I.T." Rebooting the phone doesn't help. One workaround is to go to Settings > General > Keyboard > Text Replacement and make "it" as both the phrase and shortcut. And considering that the same issue has shown up with the word "is" getting an autocorrect suggestion to "I.S," you might want to do the above workaround a second time with "is" being both the phrase and shortcut.
Since this doesn't always work, you can just turn off autocorrection altogether by going to Settings > General > Keyboard. Toggle off autocorrect. Once Apple sends out a bug fix, you can then turn autocorrect back on.
source: @Sean_w_924 via MacRumors