WFM API 429 during JMeter load test

Anyone know why the WFM scheduling endpoint keeps returning 429 Too Many Requests? Running JMeter 5.6.2 from Singapore with 20 threads. The GET /api/v2/wfm/schedule calls fail immediately after 5 requests. Rate limits seem tighter than expected for our test tenant. Using standard OAuth tokens. Any config tweaks to handle higher throughput?