Import a manually attached cluster failing

[dsputnikk]

Describe the bug

I have cut my teeth on Tanzu and I want to now automate provisioning of clusters via TMC's terraform provider. I understand how to create Terraform for a given resource, and I also understand the basics of Terraform importing.

I can successfully import a cluster I create manually thru TMC, but I have several "legacy" clusters that were attached manually.

This doc

.. specifically states that the import command is compromised of mgmt-cluster-name/provisioner_name/cluster_name.

The cluster I imported successfully which I provisioned thru TMC as a test is supervisor-name/vsphere-namespace/terraform-demo-cluster-1

terraform import tanzu-mission-control_tanzu_kubernetes_cluster.terraform-test-1 mgmt-supervisor/tanzu-simcheck/terraform-test-1 <--- Success

The clusters I've previously manually attached display (in the UI) mgmt-cluster-name = 'attached' and provisioner_name = 'attached'.

tkg-attached-cluster is an example of a cluster I've previously attached and has these displayed in the UI:

terraform import tanzu-mission-control_tanzu_kubernetes_cluster.attach_cluster_without_apply attached/attached/tkg-attached-cluster <--- Fails

Results in:

tanzu-mission-control_tanzu_kubernetes_cluster.attach_cluster_without_apply: Importing from ID "attached/attached/tkg-attached-cluster"...
╷
│ Error: Couldn't import TKG cluster.
│ Management Cluster Name: attached, Provisioner: attached, Cluster Name: tkg-attached-cluster: get request(v1alpha1/managementclusters/attached/provisioners/attached/tanzukubernetesclusters/tkg-attached-cluster) failed with status : 404 Not Found, response: {"error":"cluster not found tkg-attached-cluster","code":5,"message":"cluster not found tkg-attached-cluster"}

tkg-attached-cluster definitely exists, I see it in the TMC Console.

Reproduction steps

1. Provision TKG cluster thru kubectl
2. Manually attach to TMC
3. Attempt to terraform import
4. Failure ...

Expected behavior

I expect a successful import like in the first example

Additional context

Importing a cluster from TMC is clearly documented/thought about, but is importing previously attached clusters not supported?

I would prefer not to have to reroll the clusters in order to bring them under Terraform control.