When you schedule a task using the AT tool at a command prompt, the task appears as being scheduled in the Task Scheduler tool. When you schedule a task using the Task Scheduler tool, the task does not appear when you run the the AT tool at a command prompt.
In addition, if use Task Scheduler to modify a task originally scheduled using the AT tool, you can no longer modify the task using the AT tool.
This behavior is by design.
The Task Scheduler tool provides more features than the AT tool. Once a task is created or modified using the Task Scheduler tool, it cannot be reverted back to an AT task because the AT tool cannot interpret the additional information added by the Task Scheduler tool.