We're trying to a user in a list item but it's not working. In fact, when we validate the people picker, user is detected and we can validate our form.
[![enter image description here](https://i.stack.imgur.com/xwG6q.png)](https://i.stack.imgur.com/xwG6q.png)

But when we edit the item, the user is not recognized, and we can't save the form anymore:
[![enter image description here](https://i.stack.imgur.com/2SUpP.png)](https://i.stack.imgur.com/2SUpP.png)

When we visit the UserInfoList, we can't find this user, but when we use a REST Api request, user data is returned with his Id :
[![enter image description here](https://i.stack.imgur.com/JNfNr.png)](https://i.stack.imgur.com/JNfNr.png)

Any idea about what's happening ?