Why does the WFM schedule import endpoint rejects valid JSON payloads when migrating from Zendesk’s availability views? We are attempting to map our legacy Zendesk agent availability blocks to Genesys Cloud shifts using the POST /api/v2/wfm/schedules/{scheduleId}/import endpoint. The migration script constructs the JSON body based on the Zendesk API response, translating available status into shift objects with startTime and endTime in ISO 8601 format. However, the API consistently returns a 400 Bad Request with the error message: Invalid shift configuration: Overlapping shifts detected for agent 'ext_12345'. This is confusing because the source Zendesk data explicitly prevents overlapping availability windows. The environment is Genesys Cloud EU1 (Frankfurt), and the WFM module version is the latest release as of this week. The JSON payload includes the agentId, date, and shifts array. Each shift object contains id, startTime, endTime, and type set to WORK. The timezone is set to Europe/Paris in both the Zendesk source and the Genesys Cloud target organization. The error persists even when testing with a single agent and a single non-overlapping shift. The request headers include Content-Type: application/json and the appropriate OAuth token with wfm:schedule:write permissions. The issue seems to stem from how Genesys Cloud interprets the shift boundaries or perhaps a hidden constraint in the WFM engine that differs from Zendesk’s simpler availability model. The documentation for the import endpoint is sparse regarding specific validation rules for shift overlaps, especially when migrating from third-party sources. The error response does not provide line numbers or specific field details, making it difficult to pinpoint the exact cause. We have verified that the agent IDs match and that the dates are within the current scheduling period. The problem occurs regardless of the number of shifts imported, suggesting a fundamental mismatch in how the shift objects are structured or validated.