WebRTC Agent Desktop Fails to Register with 401 After Zendesk Migration

Why does this config cause immediate registration failures? We migrated our softphone configuration from Zendesk Talk to Genesys Cloud using the standard WebRTC endpoint settings. The environment is EU-West. When agents launch the desktop, the console shows WebSocket connection failed: 401 Unauthorized on the /v2/webchat/webrtc endpoint. The JWT token appears valid, but the registration handshake drops. Our Zendesk setup didn’t require explicit TLS certificate pinning, yet GC seems stricter. Is there a specific header mismatch or a known issue with the current SDK version 9.0.100 that breaks the initial auth challenge?