cloudwatch log not reporting value in sqs queue metric

Hi team,

I am running an application in AWS Fargate that consumes and processes messages from SQS queues.

I want to auto-scale the fargate service based on the queue length

Thsi is my CDK code

const service = new FargateService(this, "mySvc", {
      cluster,
      minHealthyPercent: 0, 
      taskDefinition: theTaskDef,
      securityGroups: [
        new ec2.SecurityGroup(this, "SG", {
          securityGroupName: "SG_name",
          vpc: cluster.vpc,
        }),
      ],
    });
  //auto-scale
    const scalingTarget = service.autoScaleTaskCount({
      minCapacity: 2, 
      maxCapacity: 40,
    });

    scalingTarget.scaleOnMetric("queueDepth", {
      metric: mySQSQueue.metricApproximateNumberOfMessagesVisible({
        statistic: "Sum",
        period: Duration.minutes(1),
      }),
      adjustmentType: AdjustmentType.CHANGE_IN_CAPACITY,
      scalingSteps: [
        { upper: 0, change: 0 },
        { lower: 100, change: +1 }, 
        { lower: 151, change: +1 },
        { lower: 201, change: +1 },
        { lower: 251, change: +1 },
       .....
      ],
      //datapointsToAlarm:1,?
      //evaluationPeriods:1,?
      metricAggregationType: MetricAggregationType.MAXIMUM,
      cooldown: Duration.minutes(1),
    });

when I deployed this infrastructure and started testing, there is no data point at all for ApproximateNumberOfMessagesVisible metric

all other metrics of the queue have values except this: ApproximateNumberOfMessagesVisible

• Approximate Age Of Oldest Message
• Approximate Number Of Messages Not Visible
• Number Of Empty Receives
• Number Of Messages Deleted
• Number Of Messages Received
• Number Of Messages Sent Sent Message Size

==> All those metrics graphs have values/data points except this one ==> Approximate Number Of Messages Visible which I'm using to auto-scale the number of tasks on the Fargate service

I'm not sure why there are no values on the Approximate Number Of Messages Visible metric, did I miss something in my CDK code? why this alarm is not breaching and is empty: ApproximateNumberOfMessagesVisible always 0 for min, max, avg, sum, last value..