[General Inquiry]: traceparent header not injected despite enabling enableW3CTraceId

[Sebastian1811]

What is your general inquiry?

I am using aws-rum-web version 1.24.0 to add RUM monitoring to my frontend apps. My apps are developed in typescript and react framework.

Client configuration

{
 sessionSalmpleRate 1,
SessionEventLimit: 0,
guestRoleArn: my_role_arn,
identityPoolid: my_identity_pool_id,
endpoint: <endpoint>,

telemetries [
   "errors",
   "performance",
   [ "http", { recordAllRequest: true, addXrayTraceIdHeader: true} ]
],
allowCookies: true,
enableXRay: true, 
enableW3CTraceId:true,
sessionAttributes: {},
}

My issue

I enabled the enableW3CTraceId flag in my RUM client configuration, expecting the SDK to inject the W3C traceparent header into outgoing API requests headers. However, the RUM client continues to inject the x-amzn-trace-id header instead.

This behavior contradicts the documentation, which states that enabling enableW3CTraceId should switch the tracing format to W3C. I followed the docs https://github.com/aws-observability/aws-rum-web/blob/main/docs/configuration.md specifically this sections:

Why I am not able to see the traceparent header? Do I have something wrong in my client configuration? Did I misunderstand the docs and this is an expected behavior?

Extra details

My frontend apps are being hosted in a S3 bucket and served using a Cloudfront distribution, I made sure to allow the traceparent header in the origin request policies and the CORS policies.

I am expecting the traceparent header in my API request so i can propagate context into my API which is instrumented using Opentelemetry, the idea is to see a trace map of my application frontend + backend.