Android 7 (Nougat): All my virtual keyboards are missing - can't find how to reinstall
Have you wiped cache/factory reset after update?
Maybe check under language and input in settings to find the device's factory installed virtual keyboard.

Response: I don't want to do a factory reset. I've added a lot of apps and customized the "look and feel" and don't want to do that all over again. The keyboard was working after all that. I'm hoping for a different solution.