Getting an Access Denied 403 error when assuming a role with Terragrunt and OpenTofu

Question

I'm trying to deploy my resources using a role but running into AccessDenied error when I run terragrunt apply. The assumed role has the AdministratorAccess policy attached to it and I've tested assuming the role using the AWS CLI.

The error I'm getting

│ Error: creating Amazon S3 (Simple Storage) Bucket (<bucket-name>): AccessDenied: Access Denied
│       status code: 403, request id: xxxxxxx, host id: xxxx
│ 
│   with module.s3_bucket.aws_s3_bucket.this[0],
│   on .terraform/modules/s3_bucket/main.tf line 25, in resource "aws_s3_bucket" "this":
│   25: resource "aws_s3_bucket" "this" {
│ 
╵

Is there anything I'm missing in my base terragrunt.hcl snippet below?

remote_state {
  backend = "s3"
  generate = {
    path      = "backend.tf"
    if_exists = "overwrite_terragrunt"
  }
  config = {
    bucket = "terraform-state-bucket"

    skip_bucket_ssencryption       = true
    skip_bucket_root_access        = true
    skip_bucket_enforced_tls       = true

    key = "${path_relative_to_include()}/terraform.tfstate"
    region         = "${local.region.aws_region}"
    encrypt        = true
    dynamodb_table = "terraform-state-locks"

    assume_role = {
      role_arn = "<redacted>"
      session_name = "<redacted>"
      external_id = "<redacted>"
    }
  }
}

generate "provider" {
  path = "provider.tf"
  if_exists = "overwrite_terragrunt"
  contents = <<EOF
provider "aws" {
  alias  = "origin"
  region = "${local.region.aws_region}"
  allowed_account_ids = ["${local.account.account_id}"]
  assume_role {
    role_arn     = "<redacted>"
    session_name = "<redacted>"
    external_id  = "<redacted>"
  }
}

EOF
}

OpenTofu version: 1.6.0 Terragrunt version: 0.54.12