GET /api/v2/analytics/queues/realtime returns empty data

Trying to pull real-time queue stats like waiting count and agents available for our adherence checks. The endpoint GET /api/v2/analytics/queues/realtime returns a 200 OK, but the data array is always empty. Here’s the query string I’m sending:

?interval=pt1s&metricNames=queue/longestWait

Is there a specific format for the interval or do I need to include a viewId? The Python SDK docs are vague on this.