Photo's saying a person is in a photo, but they are not - can't reject either!

Hey fat_geo,

Those are some great steps you tried on your own! We'd like to share some resources that may help you further isolate and resolve this behavior.

• Find and identify photos of people using Photos on Mac

• Use the People album in Photos on your iPhone, iPad, or iPod touch

Also, make sure that you're running he latest version of macOS: Update macOS on Mac

If the issue persists, we recommend that you get in touch with Apple Support team next: Contact Apple for support and service

Cheers!

You may want to open the People albums for all faces thumbnails shown below the photo, where it showing a thumbnail of john below the photo and look at all photos in these people albums. One of these albums may have a wrong keyframe, with the wrong person. Photos may have merged the albums for two people and a photo of John may have been added to a wrong person. If that should be the case, you have to weed out photos of John, that are in a wrong album and fix the key photos for all people albums.

How to Correct Merged People Albums - Apple Community