Untested sketch of a workaround for terraform.workspace not resolving in Terraform Cloud.

terraform_dot_workspace_workaround.tf

variable "org" {}

data "tfe_workspace_ids" "all" {
  names        = ["*"]
  organization = var.org
}

resource "tfe_variable" "workspace_name" {
  for_each  = tfe_workspace_ids.all.*.id
  workspace = this.key
  key       = "workspace_name"
  value     = split("/", this.key)[1]
}