See for example: https://luci-milo.appspot.com/buildbot/chromeos/betty-release/

betty/newbie are meant to create VM images, there are no HW boards associated to them. That wasn't an issue until now but it looks like the way canaries without DUTs in the lab are handled has changed. Oddly it doesn't look like it started on the exact same build, and amd64-generic-cheets (also a VM target) hasn't been impacted.