When deploying to a LXD cluster, does Juju not spread out?

I just tried deploying a lxd cluster with juju

juju deploy lxd --num-units 4 --config mode=cluster --config lxd-listen-https=true

The cluster comes up OK.

When I use that LXD cluster however and deploy 20 containers on it with juju as:

juju deploy ubuntu -n 20

juju (or lxd) doesn’t seem to distribute the deploy, but all containers end up at the same host. The corresponding containers end up in an ERROR state as you can see from my screenshot below (I think this is because my cluster hosts are too small, but I’m not sure):

image

Is the lxd cluster the problem source here or juju?