ResourceInitializationError with Fargate ECS deployment - amazon-web-services

Question

I'm fairly new to AWS. I am trying to deploy a docker container to ECS but it fails with the following error:
ResourceInitializationError: unable to pull secrets or registry auth: execution resource retrieval failed: unable to retrieve ecr registry auth: service call has been retried 3 time(s): RequestError: send request failed caused by: Post "https://api.ecr.us-east-1.amazonaws.com/": dial tcp 52.46.146.144:443: i/o timeout
This was working perfectly fine, until I tried to add a loadbalancer, at which point this error began occuring. I must have changed something but I'm not sure what.
The ECS instance is in a public subnet
The security group has in/out access on all ports/ips (0.0.0.0/0)
The VPC has an internet gateway
Clearly something is wrong with my config but I'm not sure what. Google and other stack overflows haven't helped so far.
Terraform ECS file:
resource "aws_ecs_cluster" "solmines-ecs-cluster" {
name = "solmines-ecs-cluster"
}
resource "aws_ecs_service" "solmines-ecs-service" {
name = "solmines"
cluster = aws_ecs_cluster.solmines-ecs-cluster.id
task_definition = aws_ecs_task_definition.solmines-ecs-task-definition.arn
launch_type = "FARGATE"
desired_count = 1
network_configuration {
security_groups = [aws_security_group.solmines-ecs.id]
subnets = ["${aws_subnet.solmines-public-subnet1.id}", "${aws_subnet.solmines-public-subnet2.id}"]
assign_public_ip = true
}
load_balancer {
target_group_arn = aws_lb_target_group.solmines-lb-tg.arn
container_name = "solmines-api"
container_port = 80
}
depends_on = [aws_lb_listener.solmines-lb-listener]
}
resource "aws_ecs_task_definition" "solmines-ecs-task-definition" {
family = "solmines-ecs-task-definition"
network_mode = "awsvpc"
requires_compatibilities = ["FARGATE"]
memory = "1024"
cpu = "512"
execution_role_arn = "${aws_iam_role.solmines-ecs-role.arn}"
container_definitions = <<EOF
[
{
"name": "solmines-api",
"image": "${aws_ecr_repository.solmines-ecr-repository.repository_url}:latest",
"memory": 1024,
"cpu": 512,
"essential": true,
"portMappings": [
{
"containerPort": 80,
"hostPort": 80
}
]
}
]
EOF
}