Trouble with cfn-signal: CloudFormation Stack Not Progressing Despite Successful Signal Events

I'm facing an issue with my CloudFormation stack. I have an EC2 autoscaling group in a nested stack with an creation policy defined. Despite successful signal events being sent (they are present in CloudTrail and have the correct stack name and logical resource ID of the autoscaling group) the stack never progresses to a CREATE_COMPLETE state and is ultimately rolled back due to no success signals being received. Any ideas?

Initialization of the ASG:

const eni = new CfnNetworkInterface(...)
const instanceProfile = new InstanceProfile(...)

const asg = new CfnAutoScalingGroup(this, 'autoscaling-group', {
    availabilityZones: [props.availabilityZone],
    autoScalingGroupName: `${props.env}-${props.app}-${props.hostname}-autoscaling-group`,
    maxSize: '1',
    minSize: '0',
    desiredCapacity: '1',
    defaultInstanceWarmup: 60,
})

const launchTemplate = new CfnLaunchTemplate(this, 'launch-template', {
    launchTemplateData: {
        instanceType: props.instanceType.toString(),
        keyName: props.keyName,
        imageId: props.machineImage.getImage(this).imageId,
        iamInstanceProfile: {
            arn: instanceProfile.instanceProfileArn,
        },
        networkInterfaces: [{
            deviceIndex: 0,
            networkInterfaceId: eni.ref.toString(),
        }],
        userData: Fn.base64(instanceUserData({
                env: props.env,
                class: props.class,
                hostname: props.hostname,
                stackName: Stack.of(this).stackName,
                asgLogicalId: asg.logicalId,
            }),
        ),
    }
})

launchTemplate.addDependency(eni)
asg.addDependency(launchTemplate)

asg.addPropertyOverride('LaunchTemplate', {
    LaunchTemplateId: launchTemplate.ref,
    Version: launchTemplate.attrLatestVersionNumber.toString(),
})

asg.cfnOptions.creationPolicy = {
    autoScalingCreationPolicy: {
        minSuccessfulInstancesPercent: 100,
    },
    resourceSignal: {
        count: 1,
        timeout: 'PT5M',
    }
}

The user data script has the following call to cfn-signal:

/usr/bin/cfn-signal -e $? --stack $STACK_NAME --resource $RESOURCE_LOGICAL_ID --region $AWS_REGION

A sample redacted event payload from CloudTrail:

{
    "eventVersion": "1.08",
    "userIdentity": {
        "type": "Unknown",
        "principalId": "",
        "accountId": "redacted",
        "userName": ""
    },
    "eventTime": "2023-11-17T07:13:52Z",
    "eventSource": "cloudformation.amazonaws.com",
    "eventName": "SignalResource",
    "awsRegion": "us-east-1",
    "sourceIPAddress": "redacted",
    "userAgent": "CfnTools/2.0-23 (Linux-6.1.61-85.141.amzn2023.x86_64-x86_64-with-glibc2.34) python/3.9.16",
    "requestParameters": {
        "uniqueId": "i-redacted",
        "status": "SUCCESS",
        "logicalResourceId": "redacted2B222222",
        "stackName": "dev-examplestackNestedCD33333E-1J44444444444"
    },
    "responseElements": null,
    "requestID": "redacted",
    "eventID": "redacted",
    "readOnly": false,
    "eventType": "AwsApiCall",
    "managementEvent": true,
    "recipientAccountId": "redacted",
    "eventCategory": "Management",
    "tlsDetails": {
        "tlsVersion": "TLSv1.3",
        "cipherSuite": "TLS_AES_128_GCM_SHA256",
        "clientProvidedHostHeader": "cloudformation.us-east-1.amazonaws.com"
    }
}