Promoted Builds plugin fails to trigger a downstream job

The Promoted Builds plugin does not trigger a downstream job, even though it is configured to do just that.

We are using the promotion step to trigger a deployment job. We can see that the promotion step runs, but the job is not triggered. There are no corresponding system log entries noted, and no errors in the promotion.

Screenshot of the (a) promotion step attached, (b) promotion screen and (c) promotion log showing the missing job triggering action. Note that it does nothing other than trigger this job, but instead it silently ignores the triggering.