Amazon Cognito Streams gives garbage data in the Lambda events

I have configured Lambda to read from Kinesis Stream that Cognito Sync writes to. I get see an event in Lambda logs for every CognitoSync called, but the event does not contain the data key-values that I have set in dataset. I do see the key-value being sent to Cognito in the request.

Event that Lambda gets, looks like following. How do I get the key-value in dataset from this.

2015-03-07T16:18:40.082Z    9be3582e-c4e5-11e4-be53-6f01632e7b6d
{
  "Records": [
    {
      "eventSource": "aws:kinesis",
      "kinesis": {
        "partitionKey": "us-east-1:d4bfff5d-9605-484d-9aab-0e63829b1e54-Fia",
        "kinesisSchemaVersion": "1.0",
        "data": "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",
        "sequenceNumber": "49548516359756600751834810213344902796782628138546888706"
      },
      "eventID": "shardId-000000000000:49548516359756600751834810213344902796782628138546888706",
      "invokeIdentityArn": "arn:aws:iam::111111111111:role/LambdaKinesisInvocationRole-funcog",
      "eventName": "aws:kinesis:record",
      "eventVersion": "1.0",
      "eventSourceARN": "arn:aws:kinesis:us-east-1:111111111111:stream/funcog",
      "awsRegion": "us-east-1"
    }
  ]
}