Deleting overcloud nodes failing with Mistral errors. Undercloud plan is missing

Issue

• Node delete times out in the taks wait_for_stack_status

Deleting the following nodes from stack overcloud:
- b551b300-748b-4b3b-9271-5a30a27d4911
- 0ade8139-e456-4758-9eb9-f23171a541ea
Started Mistral Workflow tripleo.scale.v1.delete_node. Execution ID: 471eb48e-bb29-4de9-b5a6-e72adfd48ab3
Waiting for messages on queue 'tripleo' with no timeout.
{u'result': u'Failure caused by error in tasks: wait_for_stack_status\n\n  wait_for_stack_status [task_ex_id=cae52ab2-4ab3-4d97-b857-1752ca343747] -> Task timed out [timeout(s)=600].\n'}