Architect Data Action HTTP POST to External API and Mapping Nested JSON Response

Stuck on mapping a nested JSON response from an external REST call within an Architect Data Action.

I am building a Python-based sentiment analysis service that ingests transcript data via the Genesys Cloud Analytics API. I need to route this data to an external model endpoint for real-time scoring. I have configured a Data Action of type “http” with the following JSON body configuration:

{
 "name": "SentimentCheck",
 "type": "http",
 "httpMethod": "POST",
 "url": "https://api.mymodel.com/score",
 "headers": {
 "Authorization": "Bearer {{auth_token}}",
 "Content-Type": "application/json"
 },
 "body": "{{transcript_text}}",
 "result": {
 "score": "$.score",
 "label": "$.label"
 }
}

The external API returns a JSON payload like:

{
 "score": 0.92,
 "label": "positive",
 "metadata": {
 "model_version": "v2.1"
 }
}

When I test this in Architect, the execution fails with a 400 Bad Request error stating “Invalid result mapping.” The documentation suggests using JSONPath for the result mapping, but $.score works for flat objects. I suspect the issue lies in how the body is being serialized or how the result object is defined. I have verified the external API is reachable and returns the expected structure. Is there a specific syntax requirement for the result field when mapping to variables in a POST request Data Action? I need to map both score and label to local variables for downstream logic.