AWS QLDB journal export doesn't include actual data

Question

I'm using the following lambda to export the QLDB data. Howerver, the export files only contain the hashes, it doesn't contain the actual document data.

The lambda:

def handler(event, context):
    ledger_name = event['LedgerName']
    bucket = event ['S3Bucket']
    bucket_prefix = event['BucketPrefix']
    role_arn = os.getenv('ROLE_ARN') or event['RoleArn']
    output_format = event.get('OutputFormat') or 'ION_TEXT'

    export_count = event['ExportCount']
    if export_count < 1:
        export_count = 1

    s3Config = {
        'Bucket': bucket,
        'Prefix': bucket_prefix,
        'EncryptionConfiguration': {
            'ObjectEncryptionType': 'SSE_S3'
        }
    }

    qldb = boto3.client('qldb')
    digest_result = qldb.get_digest(Name=ledger_name)
    address_ion = simpleion.loads(digest_result['DigestTipAddress']['IonText'])

    block_cnt = int(address_ion['sequenceNo'] / export_count)

    start_time = datetime.datetime(1900, 1, 1)
    export_ids = []
    for i in range(0, export_count):
        if i == (export_count - 1):
            end_time = datetime.datetime.utcnow().replace(microsecond=0)
        else:
            address_ion['sequenceNo'] = IonPyInt.from_value(IonType.INT, block_cnt * (i + 1))
            address_str = simpleion.dumps(address_ion,
                                          binary=False,
                                          omit_version_marker=True)
            block_response = qldb.get_block(Name=ledger_name,
                                            BlockAddress={'IonText': address_str})
            block = simpleion.loads(block_response['Block']['IonText'])
            end_time = block['blockTimestamp'].replace(microsecond=0, tzinfo=None)

            # see https://docs.aws.amazon.com/cli/latest/reference/qldb/export-journal-to-s3.html
            export_response = qldb.export_journal_to_s3(Name=ledger_name,
                                                        OutputFormat=output_format,
                                                        InclusiveStartTime=start_time,
                                                        ExclusiveEndTime=end_time,
                                                        RoleArn=role_arn,
                                                        S3ExportConfiguration=s3Config)
            print("response: {}".format(export_response))

            export_ids.append(export_response['ExportId'])
            start_time = end_time

The exported file:

{
  "blockAddress": {
    "strandId": "J3hZuXNPYEG1CXNZhZH5Mf",
    "sequenceNo": 12
  },
  "transactionId": "K5ZsAl4Oli1EcM38HHB7wb",
  "blockTimestamp": "2024-12-24T17:16:35.577Z",
  "blockHash": "13lvDEfqeoRMU6cZrj7DJvxN7G3gvuc/NDyTHxwG6Es=",
  "entriesHash": "754VaEFcWkv7DaGq7iOR5wGvnCuShaMBApmLhA7OWgg=",
  "previousBlockHash": "k3qo2OqGyWBQ4dXOdBd75dqj39R4vIhswQbllEfFEck=",
  "entriesHashList": [
    "EqC/O3Fhs9Jd0aN3os6AC8bWuKfo4oD40H5bN+oXub8=",
    "HJymp6NR63Tt8gwjERsmS2daNx9oSdIya43u9dUHZoI=",
    "Adsngx5Fehz2dNAwbULFZADhd9C1o3zuC9ckXrPQm7w="
  ],
  "revisions": [
    {
      "hash": "Du9RDX99jgUNNgYf2VJvcPHLH/QOQI04+IshjCocJ94="
    },
    {
      "hash": "xwjgpfJQYdf6Gq9z7GKKr7lckK3UhaD0vFsDROTbZFM="
    }
  ]
}