Apple may have fixed the issue that prevented iPhone owners from typing the word "I" but there are more problems yet to be fixed. The two new words that seem to be a struggle for iOS 11 users are "It" and "is." When attempting to type them, QuickType suggestions come up with "I.T" and "I.S" respectively.
Fortunately for this second round of keyboard problems, there is a way to temporarily fix it. Accessing Settings and then adding the two words as text replacements may solve the problem but some social media users claim that this does not work for them. As such, your results may vary.
Another solution is to just outright disable auto-correct and predictive text. This is far from an ideal situation but it should prevent the problem on all iOS devices regardless of version number. This newly discovered issue applies to iOS version 11.1.1 and beyond for the time being.
Not everyone is able to replicate the problem so it is somewhat unclear what the cause of it may be. Predictive text does adapt over time, making it difficult to diagnose whether there is a machine learning element at play or just a simple software bug that can be corrected in a future update.
Given that there are millions of iPhone users and only a moderate amount of complaints, it is fair to say the issue is affecting only a small number of users. Apple has declined to comment on the matter and has not yet officially recognized the bug.