Recently, our users on iPhone have been complaining that their keyboard freezes when they are using their phone. The freeze occurs every few seconds, lasting a few seconds in itself, then all the text you type in spews out all at once. If you look online, there would be a bunch of troubleshooting steps you can find on how to fix this problem, cumulating in a full refresh of the device itself. But it does not solve the root of the problem, mainly "How can i prevent this from happening again?"
A few savvy users have narrowed the problem down to the configuration of corporate email - namely Exchange Activesync configured on the built-in Mail App, that is causing the issue. How do they know this? When they remove their corporate accounts, the problem magically disappears. You can check out this old thread here, including the frustration everyone is facing:
It seems counter intuitive that a setting not related to your keyboard is causing problems to your keyboard, but there it is.
I have had difficulty troubleshooting the problem for colleagues as it is not reproducible on my device, and I had no access to a problem device for any extended duration. The best I could do was to run through the troubleshooting steps, which did not seem to work very well, and then direct them to the Apple store, where hopefully someone who knew better could do something about it.
That was, until the problem happened to me. As everyone else did, I performed the troubleshooting steps for as many steps as I could. I googled for help. I asked around with my colleagues. One thing I was reluctant to do was any form of reset on my phone though. Finally, I found one thing that made my problem go away: I deleted off a meeting invite sent from a colleague using Office 365 Exchange Online (myself I have an account on Exchange on-premise, in a hybrid environment, and am not moving online anytime soon)
Although we still don't know what is happening, there are some clues as to what is causing the problem.
1. The problem comes out of the blue, even though you may have had the same setting on the phone, not having updated it recently (this will happen even on a device updated to the latest iOS available. At the time of this writing, I am using iOS 10.3.3 on an iPhone 6)
2. The problem stays with you for a few days, then goes away
The suspected culprit: Malformed items in your Exchange account. Let me explain.
Activesync synchronizes only a few days worth of emails, calendar items/meeting invites, and reminders. When a malformed item comes into scope, it may cause your device to start showing symptoms of freezing. This malformed item was the meeting invite itself.
If you are facing an issue with your keyboard hanging, and are using Exchange Activesync through your Mail App, I invite you to try it out: First remove your calendar from your profile and see if your problem is fixed (your calendar can still be accessed through the outlook app). Alternatively, if you can do so, delete all upcoming meeting invites. Don't do this if you actually need to have the meetings in your device.
All the best