There was a bug in Windows Defender such that touching the time for a
scheduled job also incremented the date for the job--i.e. if the job was
scheduled for 9 am on the 16th, and you decided to set it to now plus 5
minutes, so you could see what happened, it would also reset the 16th to the
17th.
In the task scheduler window, go to Advanced in the menu at the top.
(control panel, performance and maintenance, scheduled tasks)
Choose View hidden tasks, to see the scheduled job.
This job will get rescheduled each time you make a change within Windows
Defenders UI to the schedule.
Choose View Log to see whether you can tell anything from that log about
whether the job is happening.
I take it that the bottom of Windows Defender's home page is not showing the
scans?
There's one other relevant log: Right-click My Computer, choose Manage.
Click on the PLUS in front of event viewer. Click on "system" to select the
System events log. Then click on View, Filter, and the Source drop-down
control--Select WinDefend as the source. This will show all System event
log messages related to Windows Defender. There should be records for start
and end of scans.
A Quickscan in Windows Defender may take only a few minutes, and no UI is
shown during the scan. If you open the Defender UI while a scan is
happening, it should show the progress.
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