Data action output mapping returning undefined despite valid json path

quick question about data action output mapping. i am hitting a wall where the success output of a custom http data action is returning undefined for a specific nested field, even though the raw response clearly contains the value. the data action calls an internal service endpoint that returns a json payload with a nested structure. i have verified the http response code is 200 and the body is valid json. the issue seems to be strictly within the json path expression used in the output mapping configuration of the data action definition. here is the relevant snippet from the data action definition json:

{
 "output": {
 "customer_id": {
 "type": "string",
 "mapping": "$.data.customer.id"
 },
 "status_code": {
 "type": "integer",
 "mapping": "$.status"
 }
 }
}

and here is a sample of the raw response body i am debugging against:

{
 "status": 200,
 "data": {
 "customer": {
 "id": "cust-12345",
 "name": "test account"
 }
 }
}

when i trace the execution in architect, status_code maps correctly to 200, but customer_id comes back as undefined. i have tried variations of the json path like $.data.customer["id"] and even flattening the response with a script step before mapping, but the core mapping seems to fail silently. is there a known limitation with how the data action engine parses nested objects when the parent key is dynamic or when the response content-type is application/json vs text/plain? i am using the latest platform api client generated from the openapi spec to update these data actions via code, so i want to ensure i am not hitting a serialization bug in the sdk when pushing the definition. any insights on why the json path evaluator would skip a valid leaf node in this structure would be appreciated.