Retrieving an image from ECR for a Fargate Service

Somewhat new to AWS, I'm trying to build a POC with CDK in python using ECR, Fargate with ALB, and an API Gateway. I've been able to publish an image to an ECR repo, but when I try pulling it into the service, it fails by hanging on the CloudFormation stack indefinitely with a lot of events stuck at CREATE_IN_PROCESS. The only error log I can find is in the cluster service logs - "exec /docker-entrypoint.sh: exec format error" which seems to be a mismatch between the image and runner infrastructure. I built the image again with --platform linux/amd64 and published it to ECR, but still getting the same errors.

The only way I've been able to get it working, is to use ContainerImage.from_registry(). I've tried both ContainerImage.from_ecr_repository(ecr.Repository.from_repository_name(self, "TestRepo", "test-repo")) and ContainerImage.from_asset(ecs.ContainerImage.from_asset(directory='./', file='Dockerfile')) to grab the dockerfile directly, both hang from the same point. Is there anywhere else I might be able to find more descriptive logging, or anything that stands out as an issue in my code? I appreciate any help or resources that can put me on the right path!

class TesttStack(Stack):

    def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
        super().__init__(scope, construct_id, **kwargs)

        # push Docker image to ECR
        docker_image = ecr_assets.DockerImageAsset(self, "TesttDockerImage",
            directory="./", file="Dockerfile"
        )

        image = ecs.ContainerImage.from_asset(directory='./', file='Dockerfile')

        # This is the only way I can get it to successfully deploy
        # image = ecs.ContainerImage.from_registry("amazon/amazon-ecs-sample")

        # Create an IAM role for the ECS task
        task_role = iam.Role(self, "TesttTaskRole", assumed_by=iam.ServicePrincipal("ecs-tasks.amazonaws.com"))

        # Fargate ECS with ALB
        ecsp.ApplicationLoadBalancedFargateService(self, "TesttWebServer",
            task_image_options=ecsp.ApplicationLoadBalancedTaskImageOptions(
                image=image,
                container_port=80,
                task_role=task_role
            ),
            public_load_balancer=True
        )

        # API Gateway is working

Dockerfile:

FROM public.ecr.aws/amazonlinux/amazonlinux:latest

# Update installed packages and install Apache
RUN yum update -y && \
 yum install -y httpd

# Write hello world message
RUN echo 'Hello World!' > /var/www/html/index.html

# Configure Apache
RUN echo 'mkdir -p /var/run/httpd' >> /root/run_apache.sh && \
 echo 'mkdir -p /var/lock/httpd' >> /root/run_apache.sh && \
 echo '/usr/sbin/httpd -D FOREGROUND' >> /root/run_apache.sh && \
 chmod 755 /root/run_apache.sh

EXPOSE 80

CMD /root/run_apache.sh