Set Participant Data action dropping custom JSON payload in IVR

I’m trying to push a custom object into the participant data store using the Set Participant Data action in Architect, but the downstream Data Action only sees the standard fields. Here’s the mapping I’m using in the action config:

{"key": "custom_order", "value": "{{flow.orderDetails}}"}

The flow variable orderDetails definitely has data since I can see it in the debug logs. Is there a specific JSON structure required for the value field to persist through the transfer? My external API keeps returning 400 because the payload is empty.

Nested objects get flattened or stripped if the downstream action doesn’t explicitly handle complex types. Try stringifying it first: {"key": "custom_order", "value": "{{flow.orderDetails.toString()}}"}. Check the delivery logs to see if the payload schema validation is rejecting the raw object.