I've run in to the same issue within a Newton environment. The delete was sent about an hour or two before I took a look, "virsh list --all" shows the instance shutoff;

[1] instance completes build

nova-compute.log:2018-03-14 20:57:52.304 46562 INFO nova.compute.manager [req-22d52f8e-e85d-4f64-b4ba-e938f4c49ed7 71aa816389589b718658b342803f9e3e9ab0baaae13597cf918694e0dbd6c0b9 a918bbf8b58a4d5bb12d7287b56fbb87 - - -] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] Took 18.21 seconds to build instance.

[2] delete call is sent

/var/log/nova/nova-compute.log:2018-03-14 20:57:32.293 22377 INFO nova.compute.manager [req-22d52f8e-e85d-4f64-b4ba-e938f4c49ed7 71aa816389589b718658b342803f9e3e9ab0baaae13597cf918694e0dbd6c0b9 a918bbf8b58a4d5bb12d7287b56fbb87 - - -] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] Terminating instance

[3] View from the compute (shows the compute choking, and the restart of the compute service to complete the delete)

nova-compute.log:2018-03-15 14:35:00.533 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 14:45:18.541 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 14:55:27.558 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 14:56:10.768 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] VM Stopped (Lifecycle Event)
nova-compute.log:2018-03-15 14:56:10.899 46562 INFO nova.compute.manager [req-0af61757-8dc4-4770-b7e3-69404ed31acd - - - - -] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:05:31.645 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:15:58.511 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:26:07.537 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:36:10.533 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:46:39.554 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 15:57:12.604 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:07:34.577 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:17:55.528 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:28:18.123 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:38:15.508 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:48:17.737 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 16:58:37.538 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:09:04.502 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:19:08.524 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:29:08.511 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:39:12.493 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:49:29.496 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 17:59:42.508 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 18:09:49.559 46562 INFO nova.compute.manager [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] During sync_power_state the instance has a pending task (deleting). Skip.
nova-compute.log:2018-03-15 18:16:15.316 1580773 INFO nova.compute.manager [req-2105ce61-a399-411d-b5be-4e327c127609 - - - - -] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] Service started deleting the instance during the previous run, but did not finish. Restarting the deletion now.
nova-compute.log:2018-03-15 18:16:15.521 1580773 INFO nova.compute.manager [req-e962e05e-a153-401a-a30b-99451fb2310f - - - - -] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] Terminating instance
nova-compute.log:2018-03-15 18:16:15.528 1580773 INFO nova.virt.libvirt.driver [-] [instance: 2d404a4e-569f-4ad3-9f81-c00fd6045d2d] Instance destroyed successfully.


Hopefully this helps... let me know if any other logs/information is needed.