Tasks getting same last run time; running outside of schedule

Question

Hello!

In a fairly fresh installation of Windows 11, I set up three Windows Defender (virus checker) tasks in the Task Scheduler. This is in addition to the existing Task which seemingly has no triggers, which as I understand, is controlled behind the scenes by Windows Defender. For my three tasks, one runs a quick scan with a trigger of at system startup. The second runs a quick scan with a trigger of 8 pm every day. The third runs a full scan every week at 5 pm on Sunday. Here are issues.

1. The two quick scan tasks have different triggers, and the built-in Windows 11 Task has no trigger. As such, I'd expect to see them each have a different Last Run Time. This seems to be the case for the daily quick scan vs the other two: my last run for the daily is 8 pm last night. However, the other two have the same Last Run Time, and it isn't the time of my last startup; instead it's the time I went to lunch.

Are these two Tasks somehow linked behind the scenes, such that whenever one is run, both get updated? I'm assuming Windows Defender automatically did a virus scan while away, hence that one getting updated. The startup one shouldn't have been updated, though, as the computer wasn't started up. When I went to lunch, I did switch my monitors and keyboard to another computer via a KVM switch. Does Windows register that as a "start up"?

2. Three of these tasks (startup quick scan, built-in Windows Defender one, and weekly full scan) seem to run anytime my computer goes idle, ignoring the triggers set for them. Going idle is not a trigger for any of these three tasks, and none of the three tasks even have a condition requiring an idle computer.

For instance, I have this computer and my work laptop on a KVM switch. Everytime I switch to my work laptop, this computer's CPU fans rev up; when I switch back to see why the CPU is getting a workout, it's because these tasks are running. They stop as soon as I switch back over. The quick scans have often finished (with the same Last Run Time), but the full scan usually has a Last Run Time slightly later and has an error message such as "The process terminated unexpectedly. (0x8007042B)". When I open the task and check the history, I'm given this explanation in Task Category, "Task stopping due to computer not idle". The task is not set up to stop when the computer becomes no longer idle.

These occur even though the computer did not just start up nor is it Sunday at 5 pm.

3. Does anyone know the behind-the-scenes schedule for virus scans? Should I just delete my custom scans, assured that Windows Defender is doing a good job?

I have tried deleting the three of my tasks (leaving the original Windows one) and recreating. That seemed to fix the daily quick scan, which used to update with all the others but now seems to only update on its schedule. The same happens with the others though. It's like there's a hidden link between them all. When I manually run a task (right click the Task, select Run), it only updates that task.

Thank you for your time and advice! :)

Answer 1

Can you provide more information on how you created these tasks? For example did you create each one in the UI or did you use scripting or code to create them? Can you export the task and reimport to confirm? Can you share the task definition with us?