To answer my own question, it does seem to work when resetting the labels :
io.rancher.container.create_agent: 'true’
io.rancher.container.agent.role: environment
Sometimes, Rancher loses this labels after a container upgrade.
Created this issue to address waht you’re seeing. Long story short, we don’t automatically copy over any io.container labels, they need some kind of UI equivalent for them to be upgraded/cloned.