Could not find Zookeeper service (after-reboot)

While running after-reboot on a monolith installation, we're getting the following error:

TASK [zookeeper : start Zookeeper service] **********
fatal: [10.1.0.4]: FAILED! => {"changed": false, "msg": "Could not find the requested service zookeeper-server: host"}

I do have an entry in my environment under inventory.ini referencing zookeeper:

[zookeeper:children]
monolith

...however, it seems the Zookeeper service may not be installed or running?
Any help appreciated!