CXone Reporting API agent state history query failing with 400

Why does this setting result in a 400 Bad Request when querying agent state history for the last 24 hours?

GET /api/v2/analytics/users/summary
{
 "dateFrom": "2023-10-25T00:00:00Z",
 "dateTo": "2023-10-26T00:00:00Z",
 "groupBy": "state"
}

The error payload returns `{“code”: “bad.request”, “message”: “Invalid query parameters”}. I need to map this data to a Pulumi stack output for IaC validation but the endpoint rejects the groupBy clause.