`juju upgrade-controller` should definitely report something, but should be reporting that it is checking for what versions are available, and then likely reporting "you're already up-to-date" (if you just did a bootstrap, then you're unlikely to be running anything but the latest version, and thus not have anything to upgrade to).
If you aren't seeing that, then I'd consider it a bug.
`juju upgrade-controller` should definitely report something, but should be reporting that it is checking for what versions are available, and then likely reporting "you're already up-to-date" (if you just did a bootstrap, then you're unlikely to be running anything but the latest version, and thus not have anything to upgrade to).
If you aren't seeing that, then I'd consider it a bug.