If you have restored your device from backup, you have probably had issues with the keyboard shortcuts that you have previous defined on your iPhone. There is a simple fix that works for 99% of people. Simply navigate to: Settings > General > Keyboard > Add New Shortcut… and then add a new shortcut. It doesn’t matter what you add because you will be able to remove it immediately after. This is just to refresh the database so that the keyboard shortcuts that you defined before still work.
If you have any questions, feel free to post below!