Cause
A person of the audience is not in allowed_user_ids of the grant.
What to do
Select only granted people.
application/problem+json
{
"type": "https://masnet.com/developers/errors/user_not_granted",
"title": "Person not granted",
"status": 403,
"detail": "...",
"code": "user_not_granted",
"correlation_id": "..."
}