title: Invalid value for field 'instance.networkInterfaces[0].accessConfigs[0].natIP': The specified external IP address is not reserved in region
body: <p>when I'm running the command:</p>
  
  <pre><code>gcloud beta compute instance-groups managed rolling-action start-update gke-playground-pool-test-1-420d5b80-grp  --version template=elk-pool-template-us-west1-3 --zone us-west1-b --max-surge 1 --max-unavailable 1 --type opportunistic --force
  </code></pre>
  
  <p>I'm getting the following error:</p>
  
  <pre><code>ERROR: (gcloud.beta.compute.instance-groups.managed.rolling-action.start-update) Could not fetch resource:
   - Invalid value for field 'resource.instanceTemplate': ''. Unable to create an instance from instanceTemplate elk-pool-template-us-west1-3 in zone us-west1-b:
          Invalid value for field 'instance.networkInterfaces[0].accessConfigs[0].natIP': The specified external IP address 'xx.xxx.xxx.xx' is not reserved in region 'us-west1'.
  </code></pre>