Task Scheduler Windows 10 : when editing a task, user account is set to Medium Mandatory Level

Question

When I edit and then save a task in Task Scheduler, the "user account' is changed.The user account which was my username is changed to "Medium Mandatory Level".

This prevents the task from running as it raises the error Task Scheduler did not launch task "..." because user "Mandatory Label\Medium Mandatory Level" was not logged on when the launching conditions were met. User Action: Ensure user is logged on or change the task definition to allow launching when user is logged off. (from Event Log, 'Applications and Service Log/Microsoft/Windows/TaskScheduler/Operational')

I can fix that by re-opening the task and setting back the user account to my username but this is cumbersome.

So how can I prevent Task Scheduler to modify the user account when I save a change made to an existing task?