Should previously identified "Faces" in the Photos app transfer to "People" in the Sierra upgrade? I can't find evidence that they did.
iMac (21.5-inch Mid 2011), iOS 10.0.2
All faces I named on El Capitan appeared in the People album after the upgrade. Is the People album empty for you?
Four "Faces" appeared, but I have a few dozen "Faces" on a different iMac tied to the same iCloud Photos account. Perhaps the previous Faces didn't sync between computers?
Faces and Persons are not supposed to sync between computers. You have to name them on every device separately. 😟 From the Photos Help:
https://help.apple.com/photos/mac/1.2/?lang=en#/phtf5e48489c
Note: People identified in the People album are not synced across devices.
Also, see this discussion: https://discussions.apple.com/thread/7676618
Photos: Faces to People Transfer
