Sourcing Autonomous Agent stuck in draft status

Summary:

After implementing the Autonomous sourcing agent as per the documentation in 26A what´s new, eligible requisitions were converted into negotiations after executing the "Process Requisition Lines with Autonomous Sourcing Assistant" , coverpage was generated, supplier recommendations were posted, but at the final state "validate and publish", the agent is giving an error and it´s not publishing the negotiation for supplier response.

error : Bad Request. Unable to parse the required payload.

error code : 27521

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Version (include the version you are using, if applicable):

26A

Code Snippet (add any code snippets that support your topic, if applicable):