Something that was noticed is that this seems to be occurring when the client machines are connected to certain Task Servers. If they manually assign those client machines to the Task Servers that seems to be more reliable, the job runs fine without having problems with their "Copy File" tasks.
Missing necessary components on the Task Server(s). Client machines were getting the Job but the "Copy File" task was not running because the necessary "Deployment Solution Task Handler" component was not installed.
For "Copy File" task to properly run, the Task Server needs to have installed:
The client machines need to have installed:
The common cause for that is "Copy File" task failing or timing out is because of missing Deployment Plugin on the client or missing DS Task Handler on the Task Server this client is registered to.