Update Human User API isn't working

I'm trying to use the v2 API

v2/users/human/

v2/users/human/

with a PUT request to update the user profile:

{
    "profile": {
        "givenName": "Test",
        "familyName": "Test"
    }
}

{
    "profile": {
        "givenName": "Test",
        "familyName": "Test"
    }
}

and while the API does return 200, the first/last names are not updated. The

changeDate

changeDate

in the response does also not refresh.