New key photo in Photos?

[SadChief]

Hi all,

In Photos/Faces: When trying to change the face appearing in the upper big cercles by choosing another photo of that person already identified as such (right click+Make Key Photo), all I get is an empty cercle with nothing inside. The person's name is still present underneath. Old face vanished and the new failed in replacing the old. I'm stuck with this big white cercle. Can't go back.
Is there any solution to this?
Big thanks for any hint

 

[SadChief]

OK after trying everything I rebuilt again the Photos library from the original iPhoto library (saved for whatever purpose before converting it within Photos - thing I warmly congratulated myself for). A previous Photos library repair didn't fix the issue.
Now assigning new key photo to a person worked as expected.
So this is a bit of experience I wanted to share with you.
Cheers.