As I have reported previously by chat, we are experiencing some strange behaviour in JIRA plugin at times. We have somewhat recently started using jira plugin to allow jenkins users to select the relevant jira issue when running the jobs.
In the jenkins job, the parameter configuration is like !!
and on the Post-build Actions we have a "Update relevant JIRA issues" action, as shown in !!
In the JIRA ticket we can see the user fire the job #1803 (there is a typo in the copy paste, but I double checked that), and we have no message whatsoever of that job, but we do have a message from the job #1806: