Windows 2019 autounattend.xml with proxmox-iso plugin

Packer
1

Looking for details on how to get Windows 2019 to pickup the autounattend.xml using the proxmox-iso plugin.

Packer v1.10.2
Proxmox Plugin v1.1.7

Have tried using additional_iso_files

additional_iso_files {
  cd_files = [
    "./Autounattend.xml"
  ]
  cd_label         = "Autounattend"
  iso_storage_pool = "local"
  }

Converting to answer file to ISO also not working.

additional_iso_files {
  iso_file         = "local:iso/autounattend.iso"
  iso_checksum     = "sha256:xxxxxxxxxxxxx"
  iso_storage_pool = "local"
}