WFM API 429s during JMeter load test in US1

Quick question, has anyone seen this weird error? with the WFM scheduling API.

Background

JMeter 5.6 in US1. Simulating 50 concurrent requests to update agent schedules via /api/v2/wfm/schedules.

Issue

HTTP 429 Too Many Requests after 10 seconds. Rate limit headers show x-rate-limit-remaining: 0.

Troubleshooting

Checked token validity. No issues. Is there a specific burst limit for WFM updates?