Default selection of index storage type not working in 4.5

When setting up a new single node, this command:
/opt/couchbase/bin/couchbase-cli cluster-init -c localhost:8091 -u Administrator -p password --cluster-port=8091 --cluster-init-username=Administrator --cluster-init-password=password --service=data,query,index,fts --cluster-ramsize=7500 --cluster-index-ramsize=2500

Doesn't choose a default storage mechanism for GSI and so you're left with a node that has all the services, but can't actually create any indexes.