The AccountId is not the issue because the Debug Log already shows that the Data Mapper Extract retrieved data successfully. The failure is at the response-return stage of the Integration Procedure. In OmniStudio, a Response Action is used to end the Integration Procedure and return data to the caller. If the Data Mapper action runs but no Response Action is configured, the internal debug data can exist while the external response remains empty. Option A is weaker because the core requirement is not only adding data to an internal response JSON property; the Integration Procedure needs a Response Action to send the final output. Option C adds unnecessary and inaccurate wording about Send JSON Path. The clean verified cause is that no Response Action was added.

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