You notice a job has been active for a long time. When you look at the log on the server you may see that it cuts off partway through the parameters and there is no indication that it started processing.
Here is an example:
-bash-3.2$ more lswpbttestq0.log
Starting maintenance queue 0 on 07/10/2015 at 08:46:48.
Waiting for a request...
Calling procedure: QMSTART - Start Queues on 07/10/2015 at 08:46:49
Parameter = Queue Numbers/Categories Value = 1,2,3,4,5,6,91,93,95