Comment 17 for bug 1604128

maas/next and a reboot fixes this for me.

root@maas:~# dpkg -l | grep maas
ii maas 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all "Metal as a Service" is a physical cloud and IPAM
ii maas-cli 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS client and command-line interface
rc maas-cluster-controller 1.9.4+bzr4592-0ubuntu1~14.04.1 all MAAS server cluster controller
ii maas-common 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS server common files
ii maas-dhcp 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS DHCP server
ii maas-dns 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS DNS server
ii maas-proxy 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS Caching Proxy
ii maas-rack-controller 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all Rack Controller for MAAS
ii maas-region-api 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all Region controller API service for MAAS
ii maas-region-controller 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all Region Controller for MAAS
rc maas-region-controller-min 1.9.4+bzr4592-0ubuntu1~14.04.1 all MAAS Server minimum region controller
ii python3-django-maas 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS server Django web framework (Python 3)
ii python3-maas-client 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS python API client (Python 3)
ii python3-maas-provisioningserver 2.0.0~rc4+bzr5187-0ubuntu1~xenial1 all MAAS server provisioning libraries (Python 3)
root@maas:~# cat /etc/apt/sources.list.d/maas-ubuntu-next-xenial.list
deb http://ppa.launchpad.net/maas/next/ubuntu xenial main
# deb-src http://ppa.launchpad.net/maas/next/ubuntu xenial main