We´re using the build blocker plugin to prevent certain jobs to be processed at the same time. There jobs are triggered indepenently by time or commits to the scm. From time to time, jobs get stuck in the queue.
What I noticed is, that jobs get stuck in the queue, in case more than one job gets queued up, eg. because one job is currently processed, which blocks the second job, and now the third one gets triggered. In case only one job gets queued up, everything looks fine.
Let me know if I can add more information which help working on this issue.
Help is greatly appreciated...