Showing Account Unknown (bunch of random numbers) under Advanced Permission settings in Windows 10

Hello,

Thank you for contacting Microsoft Community.

We understand your concern in this regard.

The Account Unknown with SID (security identifier) indicates the User Profile which is no longer exists. You can see this, when account may not be removed correctly. Since you're trying to say that there is only one User Account on your PC, I suggest you to go for a complete system scan with Windows Defender or with available Antivirus Software to see if any malware causing this issue.

You can also Microsoft Safety Scanner. The Microsoft Safety Scanner is a free downloadable security tool that provides on-demand scanning and helps remove viruses, spyware, and other malicious software. It works with your existing antivirus software. Allow it to scan your PC completely.

Keep us posted if you require further assistance.

Hello,

Thank you for getting back to us with any update.

Why you're trying to point out those SID's under Security tab?

Do you have any issue while playing those files?

If yes, what are the challenges you're facing with them?

If that is the case, you can simply ignore the same. Also scanned your PC with Antivirus software and found no issues with the same. Moreover, I believe you don't have any issues with file permissions too.

Going forward, I suggest you to keep your PC up to date with Windows Updates to make your PC run smooth.

I appreciate your cooperation in this regard.

Thank you.

If that is the case, you can simply ignore the same.  

Hello Romaneus,

We understand your concern in this regard.

I guess you may need to go with registry changes to fix this issue. Which is actually not recommended. Modifying REGISTRY settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of REGISTRY settings can be solved.

Suggest to try performing a repair In-place upgrade. A repair In-place upgrade will repair operating system files while preserving your personal files, settings and installed applications.

We recommend you to take a Backup of personal and important files in both cases to avoid unwanted situations.

How to: perform a repair upgrade using the Windows 10 ISO file

Note: If you’ve already successful activated Windows 10 on this PC, including if you upgraded by taking advantage of the free upgrade offer you won't need to enter a Windows 10 product key. You can skip the product key page by selecting the Skip button. Your PC will automatically activate later.

Keep us posted if you require further assistance.

Thank you for the reply.

I have this "issue" on two different PCs, and not only me, probably many people, maybe it was an MS update, but maybe it was like that from the beginning, i don't know. I think it would be better if Microsoft fix this problem"Account unknown", because it's not an isolated issue, especially because it's related to WindowsApps, not to third-party programs. 

 I think repair upgrade will do more harm than good. Maybe this error is not a big problem, but maybe it is, until i know for sure i can't just ignore it.

Hello Romaneus,

We understand your concern in this regard.

But as I explained, repair In-place upgrade will only repair operating system files while preserving your personal files, settings and installed applications.

I'm checking this concern in depth to see if I can able to find any useful information about this. I do agree with you that this is not related to any third party programs. For strange reason, those Unknown accounts will only appear for Windows 10 apps. I'll try to update this thread if I find something about this. 

Meanwhile, post your feedback using Windows Feedback app in this regard. Your feedback will help us to improve you experience.

I appreciate your patience in this regard.