I updated my wife's 4 gen iPad yesterday to iOS 10. There are no Memories or People showing at all. I've run iOS 10 on my own iPhone since the Public Beta came out and know you have to have the device plugged in and powered. I had the iPad plugged in all night, but not sure how to initiate the scan. It doesn't look like it's ever started. I've reset booted the iPad (power button and home button at the same time). I guess I'll try it again.