Smaller iOS updates that follow a new version are aimed at addressing bugs that users experience after the major update. On occasion, the updates do end up creating new bugs while still solving the ones they were meant to solve. This is what happened with the release of iOS 9.1. Lots of little new little bugs began to plague users but perhaps the more irritating one was the bug that affected the Contacts app. If you were to look up a contact in the Contacts app it would show you zero results. The contacts still existed on your phone, and were duly listed in the app itself. Contacts were correctly recognized in the Messages app but the update broke the search feature in the Contacts and the Phone app. If you’re experiencing the bug, the fix is finally here in the form of iOS 9.2.
The iOS 9.1 bug made it so that you could look up a contact in Spotlight search but not in the Phone or Contacts app.
The solution is to simply upgrade to iOS 9.2 where the bug has been addressed.
Once you’ve upgraded the operating system, search in both the Contacts app and in the Phone app will begin working normally. When you enter a phone number in the Phone app, it will be associated with the contact it belongs to and you can use the search in both the Phone and Contacts app to look up a contact again.
Apple never formally acknowledged the problem though people on the Apple forums were complaining about it. It seems the problem didn’t get too much attention and they were able to quietly slip a fix in with the new iOS update.