It appears that the plugin isn't checking the state of the sandbox before returning.  We see it initiate the sandbox but then it immediately returns to Jenkins and the next build step executed.  Meanwhile on CloudShell the blueprint shows as still in the Setup execution phase.  The plugin should wait (or at least have a option to wait) for the blueprint to complete;  if the next step in the Jenkins build is to process output it might have incomplete data if the blueprint hasn't finished