Faces lost or reset in Photos

Your recent system update might have removed the named faces, temporarily. Did you update from an earlier Ventura version or from macOS 12?

When we upgrade the system to a version, that has an improved face detection, Photos will scan all photos again for faces. And the for the photos, where we manually assigned the faces circles, because Photos could not detect a face, or for photo, where Photos has now found the face in a slightly different position, we will temporarily not see the faces, until the new scan for faces has finished. Then we will have to confirm the faces again, using the "Confirm additional faces" dialog in People.

I have seen faces vanishing several times after a system upgrade, whenever the face detection and face recognition has been updated. Most faces came back once the new faces scan had done the work, but it took a few weeks.

Because the named faces are not stable across system versions and when synced with iCloud to other devices with different system versions, I am taking the precaution to tag all photos with named faces with keywords with the names oof the people in the photos. This way I can check with a smart album with the rule "Keywordd is " and "person is", if the named faces have changed. How to use Keywords to Back Up the Named Faces in Photos and Improve the Search for People … - Apple Community

I am not sure, if your temporary use of the shared library could have caused this. We cannot see the People album, when we are only viewing the Shared iCloud Library. The faces I named in the photos I have moved to the Shared Library renmained.

I also am seeing odd behavior in Photos after restoring my rather large Photos library to a MacMini 2018 i7 2 TB. The faces are being recognized haphazardly, and I've seen the vague message at the bottom: "Photos will finish updating your People when you're not using the app."

Does anyone know what "when you're not using the app" means? Open, but in background? Foreground but no keyboard or mouse activity? Closed altogether (ie, it's doing it in the cloud)?

Is there a way to accelerate the facial scanning? (I know how to name manually, and to merge images of the same person that have been sorted into different names.)

PS, I like the suggestion about tagging with a keyword name...very useful for exporting photo albums to non Mac users.

Photos needs much more time. And it is not wasting time on updating the status message. Just keep your mac from falling asleep and restart Photos and your mac once a day, just in case that the Photos background processes should have crashed. On my Mac with only 50000 photos and videos the new Faces scan took three weeks.

As you have repaired the library Phots will also have needed to upload your complete library again into iCloud and need time to repeat the object recognition and scene analysis and many other background tasks, so the face detection and recognition will occasionally be paused to finish the other tasks.

Thanks, I figured that might be the case. I'll go make another coffee.