exec format error trying to use 64-bit ARM architecture for Fargate launch type

I am trying to leverage Amazon ECS 64-bit ARM architecture for https://hub.docker.com/r/arm64v8/nginx and other arm64 images. However, I am getting the error: "exec user process caused: exec format error" during service creation phase. Fargate amd64 tasks with amd64 images run without this issue. According to this article - https://docs.aws.amazon.com/AmazonECS/latest/userguide/ecs-arm64.html my configuration must support 64-bit ARM workloads:

• Region: Asia Pacific (Tokyo) ap-northeast-1
• Fargate platform version: 1.4.0
• Docker compose

version: "3.9"
services:
  nginx:
    image: "arm64v8/nginx"
    x-aws-policies:
      - "arn:aws:iam::aws:policy/AmazonSSMFullAccess"
x-aws-cloudformation:
  Resources:
    NginxService:
      Properties:
        EnableExecuteCommand: true
    NginxTaskDefinition:
      Properties:
        RuntimePlatform:
          CpuArchitecture: "ARM64"
          OperatingSystemFamily: "LINUX"