Been there, done that, many times. It gets me a message “No people found” I had turned off Facial Region (Under People) and this is what I can’t turn back on. See my other posts on the community for detail explanation.
Do you have a particular folder selected which might not contain faces to be recognized?
You need to select All Photographs panel in the Library module and then, go to People's view.
Done that. Doesn’t work. Screenshots attached.
This is what the menu shows
I did not receive the shortcut
Refer : The specified item was not found.