WFM Schedule Import 422 Error during Zendesk Migration

Stumbled on a weird bug today with the Workforce Management schedule import API. We are migrating forecasting data from Zendesk to Genesys Cloud, expecting a smooth transition.

The POST to /api/v2/wfm/schedules returns a 422 Unprocessable Entity error. The JSON payload matches the schema exactly, but the system rejects the shift patterns.

Is there a specific timezone format required for Europe/Paris that differs from the Zendesk export structure? The documentation is vague on this mapping.