If a CatDV Worker Node has jobs queued and the checkbox checked to activate the Worker process but no job is running, check the number of jobs in the queue. If the total number of jobs is large (typically 10,000+) the Worker Node may stall without warning or error.
Simply delete some of the old, completed jobs and the queue will start to run jobs. This was noticed first in versions near 6.1.5 and is likely patched in later versions so you may want to contact support and update your Worker Node. (Be careful to also update the command line binary.)