Analytics Query 429 during JMeter ramp on US1

Could someone clarify why the analytics endpoint fails under load?

Background

Genesys Cloud US1. JMeter 5.6. Testing concurrent report generation. Simple query for call volume last 24 hours.

Issue

Endpoint: /api/v2/analytics/conversations/details/query.
Getting 429 Too Many Requests at 30 concurrent threads. Request body is minimal JSON. No complex filters.

Troubleshooting

Checked rate limit headers. Limit is 100 per second. Script stays well below this. Retries fail immediately. Is there a hidden concurrency limit for analytics?