Terraform's resource `aws_cloudformation_stack_set_instance` does not grab my parameter_override

Question

I'm confused on how this works and there's not much documentation so I'm hoping to give a clear problem to my question.

I have this code which creates StackSets for my service. I want to create buckets that are associated with the AWS Accounts I have which I created a module to interact with. I'll go 1:1.

Here is my module as an example:

locals {
  account_alias = {
    "merry" = "2342342342343"
    "alpha" = "234234234234"
    "sandbox-fuu" = "234234234234"
    "sandbox-fire" = "290823749834"
    "sandbox-doo" = "23423423423"
  }
}

output "map" {
  description = "Map of human-friendly account alias to string numerical account ID (strings because leading 0 are important)"
  value       = local.account_alias
}

I then use this resource to loop through my aws_cloudformation_stack_set_instance:

resource "aws_cloudformation_stack_set_instance" "instance" {
  for_each       = var.environment == "sandbox" ? { for key, value in module.account_alias.map : key => value if can(regex("^sandbox-", key)) } : module.account_alias.map
  depends_on     = [aws_cloudformation_stack_set.base]
  region         = var.region
  stack_set_name = aws_cloudformation_stack_set.base.name

  account_id = each.value

  parameter_overrides = {
    bucketName = each.key
  }
}

When I run terraform plan, I get the output of the 3 resources that have sandbox-* accounts which works correctly. The output of the plan is like this:

  + resource "aws_cloudformation_stack_set_instance" "instance" {
      + account_id          = "23432432433e33"
      + id                  = (known after apply)
      + parameter_overrides = {
          + "bucketName" = "sandbox-fire"
        }
      + region              = "us-west-1"
      + retain_stack        = false
      + stack_id            = (known after apply)
      + stack_set_name      = "fuu-fuu-sandbox"
    }

Now here is where the issue arises. When I run terraform apply, I have a baseline aws_cloudformation_stack_set which uses the YAML file for my bucket creation. bucketName is used as an empty string which I would like to use the parameter_overrides to replace the value for the designated AWS account but what happens is I do not get the value but the value of the empty string for all environments ''. What would I need to do to resolve this error?

Parameters:
  bucketName:
    Type: String
    Default: ''

Resources:
  GlobalS3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      VersioningConfiguration:
        Status: Enabled
      BucketName: !Sub fire-bucket-${bucketName}-${AWS::Region}
      AccessControl: Private
      LifecycleConfiguration:
        Rules:
          - Id: MoveTfStateFilesToStandardIAToGlacierToNothing
            Status: Enabled
            NoncurrentVersionTransitions:
              - TransitionInDays: 30
                StorageClass: STANDARD_IA
              - TransitionInDays: 60
                StorageClass: GLACIER
            NoncurrentVersionExpirationInDays: 730

EDIT: This will show the aws_cloudformation_stack_set where it calls the YAML file for CF:

resource "aws_cloudformation_stack_set" "base" {
  name        = "fuu-fuu-${var.environment}"

  template_body = file("${path.module}/files/code.yaml")

  parameters = {
    MasterId = var.master_account_id
  }

  administration_role_arn = var.stack_set_administration_role_arn
  execution_role_name     = var.execution_role_name
}

Answer 1

This was resolved in a manner which dealt with my Terraform code. Thank you for the support.