Docker client config - plugin config not working

Hey - trying to configure docker on the client.

My existing config inside /etc/nomad.d/client.hcl:

client {
  enabled = true
  options {
    docker.volumes.enabled = true

This works as expected, volumes work as expected and the Nomad UI reports this under Client:

I know this is config method is deprecated, and I need additional config options, so I want to switch over to using the Docker plugin stanza. Adding the following to the same /etc/nomad.d/client.hcl does not work:

plugin "docker" {
  volumes {
    enabled      = true
    selinuxlabel = "z"
  allow_caps       = ["net_admin"]

The UI shows that volumes are not enabled and if I try to run a container with net_admin capabilities I get this in the task log:

Anything I am missing with he plugin config?

Should have mentioned my Nomad version info:

nomad.version 1.1.6
nomad.revision b83d623fb5ff475d5e40df21e9e7a61834071078