To resolve this, follow the steps below:
Check if Task Servers are running
Search Task Scheduler on server and open.
Select Task Scheduler Library.
Select the job Start Task or Start Task Server.
In the security options that the user who's set on the account has the setting Run Only when user is logged on selected.
So if the Task Servers didn't start then the user highlighted in the task scheduler task was not logged on so the task servers would not start and no jobs would be processed.
Restart the Task Servers
Task servers require the Windows account and, if running email-related tasks, an Outlook application logged in and running at all times. Often task server failures are caused when the account has been logged off by a system restart. This means you need to manually log back into the associated Windows account then start the task servers manually.
Once logged back onto the correct account:
Navigate to \\servername\prodisk\proclaim\batch\tasksdesktopicon.
Right-click taskserver.exe then click Run as administrator.
Alternatively:
Open Task Scheduler.
Right-click on Start ATS.
Click Run.
If you are still having issues with your task servers, please raise a new case online and reference the title of this article.
NOTE: If task servers are running and a task isn't staying in the schedule just update the job and disable and save. Then update it again and enable and save then it should appear in pending list.