Statistics API /api/v2/analytics/queues/realtime returning 400 Bad Request in n8n

My configuration keeps failing for fetching live queue metrics.

I am building a self-hosted n8n workflow to poll real-time queue statistics (waiting count, agents available) every 30 seconds. The goal is to trigger alerts when wait times exceed thresholds. I am using the standard HTTP Request node with OAuth2 credentials configured correctly, as verified by successful calls to /api/v2/users/me. However, the specific Statistics API endpoint returns a 400 Bad Request error immediately. I suspect the query parameters for interval or groupBy are malformed, but the documentation is ambiguous about required fields for real-time snapshots versus aggregated data.

Here is the current request configuration:

{
 "nodeVersion": 2,
 "parameters": {
 "requestMethod": "GET",
 "url": "https://api.mypurecloud.com/api/v2/analytics/queues/realtime",
 "options": {
 "qs": {
 "interval": "now-1m/now",
 "groupBy": "queue",
 "queueIds": "{{ $json.queueId }}"
 }
 }
 }
}

The error response body is generic: {"code":"bad.request","message":"Invalid query parameters."}. I have tried removing groupBy and using queueId as a path parameter instead, but both result in 400 errors. Is the interval format incorrect for real-time data, or is there a specific header required for this endpoint that n8n is omitting? I need to know the exact parameter structure to stabilize this automation pipeline.