Admin handler 'shclustercaptainkvstoremigrate' not found.

[TheBravoSierra]

I'm trying to run the below command on my search head cluster deployer: 
splunk start-shcluster-migration kvstore -storageEngine wiredTiger -isDryRun true

I receive the following message: 
Admin handler 'shclustercaptainkvstoremigrate' not found.

This is after I have edited $SPLUNK_HOME/etc/system/local/ on each search head in the cluster, following: Migrate the KV store storage engine - Splunk Documentation
 

[kvstore]
storageEngineMigration=true

Please advise.