WFM Scheduling API 502 Bad Gateway at 10 concurrent threads

Why does the Workforce Management scheduling endpoints are failing under minimal load?

Running JMeter 5.6.2 from Singapore. Targeting POST /api/v2/wfm/schedules/bulkupdate. Single thread works fine. At 10 concurrent threads, I get consistent 502 Bad Gateway errors. No 429s.

Environment:

  • Genesys Cloud Production
  • JMeter 5.6.2
  • Singapore data center
  • 10 threads, 0 ramp-up

Logs show the request times out at the proxy layer. Is this a known capacity limit for WFM APIs?