Windows 10: Is the Defender GUI bug hiding defined exclusions fixed?

[German]I take the topic again. Does Microsoft Defender show defined scan exclusions under Windows 10? Or is the GUI bug I mentioned in this blog still present after Defender updates?


What is the Defender GUI bug?

Since an update of the engine to the anti-malware client version 4.18.2010.4, Microsoft Defender has a display bug regarding user-defined exclusions. Users suddenly find that defined exclusions are no longer displayed in the GUI and no new exclusions can be defined. But the PowerShell shows that the exclusions are still present.

I became aware of the situation through a request from a reader, that has been forwarded by German heise magazine to me. But also at as well as in the Microsoft Answers Forum you can find user complaints concerning this behavior. I had covered the topic within my blog post Windows 10: Does Defender forget defined exclusions?

Distinct user feedbacks

In the German comment here, blog reader Tom writes on October 28, 2020, about the GUI display error:

With today's update to version 4.18.2010.6, the exclusions have become visible again!
Just a "bug as a service" after all…

But blog reader René S. (who had initiated the topic at heise) contacted me by e-mail on November 2, 2020. René described his experiences like this:

today I received in the host system (build 19042.610) and in the VM (20246.1) again an update of Defender to the antimalware client version: 4.18.2010.7.

The problem is still there and in the host system the GUI does not show any previously defined exclusions and no additional exclusions can be created via the GUI.

But the previously created exclusions are visible via PowerShell (Get-MpPreference). In the VM in which I have not created any exclusions, the GUI also says "No existing exclusions", but you cannot create exclusions.

The first time I tried and selected e.g. a file or folder, the user account control appeared once to confirm the process, but the exclusion was not visible in the GUI afterwards.

At further attempts, i.e. from the 2nd attempt on, there was no query from the User Account Control but no exclusion was optically displayed in the GUI. However, these exclusions, which I wanted to create via the GUI for testing purposes, are visible via PowerShell, although the GUI still showed "No existing exclusions".

Currently there is this German comment from Info which reports that the exclusions are displayed. It indicates that not all Defender users are affected, but only some. From René I know that he received an anti-malware client version on his machine that should not have been installed on his machine (he does not participate in any developer program, but the buggy anti-malware client version was intended for developers). Something went wrong and some people probably got a bug installed on their systems via update. Hence the question to the users who were affected by the GUI display problem: Did an update of the antimalware client version do anything to the problem?


How to fix

Addendum: The blog reader, who reported me his case, told me his steps afterwards how he could fix the problem. The procedure of the reader was as follows:

  1. Installation of KB4586853, which raised Windows to build 19042.661
  2. Inplace upgrade repair with an ISO of Windows 10, which has build 19042.630

The reader writes that after updating with the ISO and then restarting, the problem with the 'missing' exclusions has been fixed and is gone. He can now create and remove exclusions from Windows Defender via the GUI, and he can also see all exclusions he created blindly via the GUI when it didn't work.

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