It looks like that all the StackStorm images on DockerHub (https://hub.docker.com/u/stackstorm) are missing latest tag.
I'm not sure if that's a feature or a bug, I'm leaning towards a bug during the release process.
Not having the latest tag, means all the commands in the docs, etc. which refer to Docker images without explicitly specifying a tag (e.g. 3.3.0) are failing.