WFM Business Unit 400 via Terraform - Duplicate Key

Is it possible to deploy a new WFM Business Unit when the external_id conflicts with a legacy soft-deleted record?

“The externalId must be unique across the organization.”

Provider v1.68.4. Region au-1. The apply fails with a 400 Bad Request. Terraform state shows the resource exists, but the UI does not. Cannot overwrite. Cannot delete via CLI. Stuck.