Why is Photos People is ignoring one of my sons...
After updating to 10.3.3 I had to reorganize, yet again, the People tab of Photos. It seems the tab has been dummied-down. I'm no longer able to select unidentified faces in the tab and assign the to someone and I can no longer hide and unhide people.
Despite that, after hours of work, I managed to get everyone I want organized in the People tab like I want. Except for one of my sons. I can identify his face in Photos or Moments, or anywhere, and Photos (App) offers his name when I type the first two letters of his name, but he never shows up in People. Others whose faces I've IDed show up. Very frustrating.
MacBook Pro with Retina display, macOS Sierra (10.12.4), Late-2013
howapple - hello
The person album for your son may be hidden. You hide persons by deleting the album. To add a hidden album back select a photo of the person, where the face is circled and view it enlarged. then swipe up to reveal the faces thumbnails below the photo and click the thumbnail with the face of your son to open his album. At the bottom of the album click "add to people"