UnauthorizedError when publishing to local MQTT

Hey folks,

Trying to get IPC working for custom components, and I've hit a wall.
I've configured local IPC according to the documentation (as far as I can tell), but whenever I publish to a topic I get an UnauthorizedError. I assumed that this was a misconfiguration of access control in the recipe, but I don't see any differences between my recipe and the examples. Any help would be much appreciated.

Here's the relevant bit of the recipe:

ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        "my.custom.component:pubsub:1":
          policyDescription: "Publish access for database interface."
          operations:
            - "aws.greengrass#PublishToTopic"
          resources:
            - "*"

and here's the code that publishes:

def publish_to_topic(topic, message):
    logger.info(f"sending: {message} to {topic}")
    request = PublishToTopicRequest()
    request.topic = topic
    publish_message = PublishMessage()
    publish_message.binary_message = BinaryMessage()
    publish_message.binary_message.message = bytes(dumps(message), "utf-8")
    request.publish_message = publish_message
    operation = ipc_client.new_publish_to_topic()
    operation.activate(request)
    future = operation.get_response()
    try:
        future.result(TIMEOUT)
        logger.info('Successfully published to topic: ' + topic)
    except concurrent.futures.TimeoutError:
        logger.error('Timeout occurred while publishing to topic: ' + topic)
    except UnauthorizedError as e:
        logger.error('Unauthorized error while publishing to topic: ' + topic)
        raise e
    except Exception as e:
        logger.error('Exception while publishing to topic: ' + topic)
        raise e

TIMEOUT = 10
ipc_client = awsiot.greengrasscoreipc.connect()
topic = "my/test/topic"
message = {
    'foo': 'FOO',
    'bar': 'BAR'
}
publish_to_topic(topic, message)