Task definition override - Fargate - Jenkins AWS ECS Plugin

I have an ECS cluster(Fargate) named test and a task definition that runs the nginx image as below. I am trying to test the task definition override functionality.

And am trying to use and run the following on Jenkins:

ecsTaskTemplate(
    cloud: 'test',
    label: 'fargate',
    name: 'fargate', // Reusing the label as a name makes sense as long as it's unique
    containerUser: 'ubuntu',
    remoteFSRoot: '/home/ubuntu',
    overrides: [],
    taskDefinitionOverride: "arn:aws:ecs:ca-central-1:123456789:task-definition/nginx:12"
) {
  node(fargate) {
    stage("I dunno why you say goodbye"){
      sh 'echo hello'
    }
  }
}

The error on running this is:

[test-fargate-mkcz4]: Error in provisioning; agent=com.cloudbees.jenkins.plugins.amazonecs.ECSSlave[test-fargate-mkcz4]
java.lang.NullPointerException
    at com.cloudbees.jenkins.plugins.amazonecs.ECSService.runEcsTask(ECSService.java:426)
    at com.cloudbees.jenkins.plugins.amazonecs.ECSLauncher.runECSTask(ECSLauncher.java:213)
    at com.cloudbees.jenkins.plugins.amazonecs.ECSLauncher.launchECSTask(ECSLauncher.java:149)
    at com.cloudbees.jenkins.plugins.amazonecs.ECSLauncher.launch(ECSLauncher.java:110)
    at hudson.slaves.SlaveComputer.lambda$_connect$0(SlaveComputer.java:294)
    at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
    at jenkins.security.ImpersonatingExecutorService$2.call(ImpersonatingExecutorService.java:71)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

What could be wrong here, I am assuming this would create a template and then a task on Fargate.