Speech Analytics API returns empty transcript for completed calls

We’re pulling transcript data for QA using the /api/v2/analytics/speech/text/transcripts endpoint. The call status is completed and the transcriptionStatus shows finished, but the transcript object in the response is empty.

We’ve verified this isn’t just a delay. The call ended two hours ago. We’re using the Python SDK with a valid OAuth token. Here’s the payload structure we’re seeing:

{
 "transcripts": [
 {
 "id": "abc-123",
 "transcriptionStatus": "finished",
 "transcript": []
 }
 ]
}

Is there a specific permission missing on the service account? We have analytics:speech:view and analytics:speech:export. The logs show no 403 errors, just empty data. What am I missing?