Payload too large for Async Inference on Sagemaker

I got it up and running by doing it slightly different

def infer_async():
    sagemaker_runtime = boto3.client("sagemaker-runtime")

    # Specify the location of the input. Should be JSON with the input audion file (example in 02_deploy_whisper-Async.ipynb notebook)
    input_location = "s3://async-inf/input.json"

    # The name of the endpoint. The name must be unique within an AWS Region in your AWS account.

    # After you deploy a model using SageMaker hosting
    # services, your client applications use this API to get inferences
    # from the model hosted at the specified endpoint.
    response = sagemaker_runtime.invoke_endpoint_async(
        EndpointName=endpoint_name,
        # ContentType='audio/mpeg',
        InputLocation=input_location,
    )
    print(response)