placement initiatives for hulk-smash with specific unit offsets not working

I have a deployer.yaml config that looks like:

placements:
  services:
    ceph-mon:
      to:
      - lxd:storage=1
      - lxd:storage=2
      - lxd:storage=3

services:
  inherits:
  - placements
  services:
    ceph-mon:
      charm: ceph-mon
      num_units: 3
      bindings:
        "": oam-space
        public: ceph-public-space
      options:
        expected-osd-count: 84
        monitor-count: 3
        source: distro
        customize-failure-domain: True

I receive the error:

2017-04-20 19:46:15 [ERROR] deployer.deploy: Invalid application placement ceph-mon to lxd:storage=1
2017-04-20 19:46:15 [ERROR] deployer.deploy: Invalid application placement ceph-mon to lxd:storage=2
2017-04-20 19:46:15 [ERROR] deployer.deploy: Invalid application placement ceph-mon to lxd:storage=3

My environment has the following units already deployed as ubuntu charms:

Unit
compute/0
compute/1*
compute/2
compute/3
compute/6
compute/8
compute/10
compute/11
compute/13
compute/14
compute/15
compute/21
compute/24
compute/26
gateway/0*
gateway/1
gateway/2
infra/1*
storage/3*
storage/5
storage/6
storage/7
storage/8

I'm using juju-deployer from within mojo, and it's the juju-deployer shipping with mojo 0.4.5 from the mojo-maintainers ppa.

This same error exhibits whether I use lxd:storage=1 or lxd:compute=0 or compute=0 or storage=0 formats. I can't target specifically deployed units as demonstrated in seranade: to: lxc:wordpress=2 in docs here: https://pythonhosted.org/juju-deployer/config.html#placement

juju-deployer 0.10.0~bzr208~60~ubuntu17.04.1~bzr210~61~ubuntu16.04.1
juju version
2.0.2-xenial-amd64
mojo --version
0.4.5