Manually adding faces to Photo does not work as described in the manual

As macgirldc wrote - you can just click into the name field wherever the circle is, and only then adjust it. However, this way the faces thumbnail may be wrong, initially.

You can also click somewhere into the background - somewhere outside any faces circle to bring the focus back to the photo you are working with. Then you should be able to move and adjust the faces circle.

if none of this helps, quit photos and restart it. And if all fails, restart your Mac.

See: Work-Around: What to do, when the Faces Circle is jumping around - Apple Community

o13g wrote: … when you try to move them/change the diameter of the circle, the entire photo moves.

Yeah, that happens. Sometimes the circle refuses to move, because Photos thinks you're still in the info window and you want 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.  

Ahh--once again léonie and I are typing at the same time! We've both had to deal with this stuck circle problem!

Can you upgrade your Mac to macOS 15 Sequoia? I noticed the problem with the manually added faces circles first in macOS 10.15 Catalina, and it persisted for several system versions. It seems to be fixed in Sequoia, however, at least, I have not noticed it any longer in the current system version so far, but the upgrade might not be possible for a 2017 MacBook Pro.

Are you sure that your photos library is not corrupted? If so, you might want to restart your mac to see if the issues perisist

Add a name to the circle, then move it.

Gee, I sure hope you have a backup of your Photos Library! There is not end to the corruption like this app could cause by mucking around in the Photos database! Good Luck with that!

The same applies to "Cleaner" type apps that mess around in the Photos Library. Be careful with the apps you use!

Indeed. we should not use it on our main libraries without more than one backup, and the backups should be tested. Face Explorer is a great project by Tim Felix Beyer, but I would take the author's caution seriously. He stated in the documentation to the app:

"Warning: Although everything should be safe, I am not responsible for any data loss - proceed at your own risk

...

This project is my first macOS application in Swift. 

...

• (Work in progress) Enables users to assign names to the faces right from the app. This is a bit scary because it requires writing to the photos library database."

léonie wrote: He stated in the documentation to the app:

"Warning: Although everything should be safe, I am not responsible for any data loss - proceed at your own risk

...

This project is my first macOS application in Swift. 

...

(Work in progress) Enables users to assign names to the faces right from the app. This is a bit scary because it requires writing to the photos library database• ."

I read that, as well, and it made my skin crawl! This sounds very exciting, but I would only use it on a Photos Library that I wouldn't mind losing.

I think that a recommendation to try this out should be accompanied by an appropriate full warning, like

"use this app only on a copy of a Photos Library that you wouldn't mind losing."