Photos app on Mac will not allow me to identify faces

ridgecritter wrote: …when I find an unclassified image of a person (like when I just browse the library), who is identified in the People & Pets collection, how do I tell Photos to identify that unclassified person as Mr/Ms X?

"unclassified image of a person" could mean two things: it could be someone like this:

with "unnamed" under him. Photos has recognized this as face, but doesn't know who it is. You can type in the name. Then the characteristics of this face will be incorporated in this person's database to help identify more pictures.

Or "unclassified image of a person" could mean that Photos has not realized that this is a face. For that case, inn the info window, below the Keywords field, is the Face ID field, and in there is a little + sign in a circle:

When you click on that, a little circle appears in the center of the picture, and you can resize it and move it to the face you want to record:

Then you can enter the name, like Charley or Prince of Wales, or whatever. Then, if Charley has no People album, one will be created for him, and this picture will go there. Later, if you need to change the name for some reason, you can do that in the People album, maybe making it King Charley III, or something.

With this situation, where Photos hasn't recognized Charles' profile as a face so you've had to manually indicate the location, the characteristics in this image won't be added to Charley's data, and it won't affect future IDs.

The one problem we sometimes have is that the circle refuses to move, because Photos thinks you're still in the info window and it wants to drag the picture there, or something like that. In that case you need to tap on the picture to let Photos know you mean the picture, and then you can move the circle. Or, you can just type the name first, and then move the circle.

Does this work for you?

Where are you looking for these face names? The part about "face name in the upper left right above the image" makes me think that you are looking in the People album, is that right? This is what People shows for my Great-Aunt Altha

with her name in the corner, and there are no names in the pictures. In People albums, the name only appears when you open an individual picture.

It seems like in other places you are describing a completely different view, probably like this:

and you are saying that there is not face or + sign available, is that right? And if there is no face there, then this pictures isn't in a People album, is that right?

Are you using iCloud Photos to synchronize the Libraries on your devices? I see that you have tried rebuilding the Library, so try these things to help narrow things down. Unfortunately, Face Naming takes quite a bit of time, so you may have to wait a day or two see what happens.

• Re-start in Safe Mode. This bypasses certain potentially disruptive processes, and it often helps. Safe Mode is different for different computers, so see this: 

           Start up your Mac in safe mode - Apple Support 

• Use another library if you have one, or make a small test Library with a few pictures in it and see if the same thing happens. You can create a new Library by closing Photos and then option-clicking on the Photos icon.
• Make a new user and see if the same problem recurs with it

The idea is to find out if the problem is with the Library, with your account, or with caches and login items, and stuff like that. One of these steps may fix the problem, but their failure to work also helps figure out what's happening.

Let us know what happens…

Have you installed and run any "cleaning", "optimizing", "speed-up", anti-virus or VPN apps on your Mac?

Try launching the library with the Option+Command keys held so to rebuild the library. Then check to see if the problem persists.