Thumbnails in File Explorer only for images/videos

Over the weekend I set up my father's new PC, with Windows 11. I'm getting some unwanted behavior, that differs from my own devices.

It concerns thumbnails versus file icons in file explorer.

On my own devices: Always show icons, never thumbnails is OFF. I see thumbnails for images/videos/music files, but NOT for other files types like Word documents and PDF's. Which is what I want.

On my father's new PC: Always show icons, never thumbnails is OFF. I see thumbnails for everything, which is not what we want.

Why is it behaving like that on my devices? What did I do to make it behave like that? I did many web searches, but I haven't run into a solution yet.

I do have K-Lite Mega Codec Pack installed on PC, which comes with Icaros thumbnail provider. Could that be breaking thumbs for non images/video/music files? Which would be a nice side effect. But it is not installed on my laptop, so...

Why can't Microsoft just gives us more control. Why would anyone want thumbnails for pdf and docx files.

It depends what applications are registered to open the other file types. For example if PDF is associated with Microsoft Edge (default), you see a certain icon. If you install Adobe Reader or Adobe Acrobat and is associated with that, you see a thumbnail of the first page. Similarly for other extensions.

Turn off thumbnails via explorer option
Clear the icon cache via Cmd
Set Klite codec tweak tool to show desired thumbnails
Clear icon cache again
Reboot

spapakons said:

It depends what applications are registered to open the other file types. For example if PDF is associated with Microsoft Edge (default), you see a certain icon. If you install Adobe Reader or Adobe Acrobat and is associated with that, you see a thumbnail of the first page. Similarly for other extensions.

Click to expand...

On all three devices Adobe Reader is installed and set as default pdf app. In Adobe Reader's settings, thumbnails are set to off. Yet, I do not get the same behavior on all three devices.

dacrone said:

Turn off thumbnails via explorer option
Clear the icon cache via Cmd
Set Klite codec tweak tool to show desired thumbnails
Clear icon cache again
Reboot

Click to expand...

The following thumbs are controlled by that tool:

Image files are not impacted? If I were to try this one my father's pc, then how to get the image thumbs back, if I turn off thumbnails via the explorer settings and re-introduce just the below?

Concerning the following regkey:

I do not seem to have it on my pc/laptop, but it is there on my father's device. Maybe I should just delete it and see what happens.

I won't be near his device for a while. But I'm open to more thoughts on this topic.

Is there a difference in this respect between Windows 11 Pro en regular Windows 11? As my two devices have 11 Pro installed and my father's pc does not.

Visiting my father again, so I thought I'd take another stab at this.

Turns out, OneDrive is the culprit and specifically the Files On Demand feature. If the folders and files are in the OneDrive folder and if Files on Demand is on. then OneDrive will generate the thumbnails, for all kinds of files. Provided the File Explorer setting "Always show icons, never thumbnails" is off.

If I quite OneDrive, it behaves as expected, only thumbnails for folders and image/video files.

So, for example PDF and Word files, it doesn't matter if a thumbnail previewer is registered in Windows. If thumbnail previews are on in Word or Adobe Reader or not. OneDrive will force thumbnails if Files On Demand is on, period.

Now comes the real issue, Files On Demand is on by default for new installations, it cannot be turned off entirely. You can only choose between two options, Free up disk space and Download all files. The second option will still keep some parts of the feature active and thus keep forcing thumbnails. On my own devices, this was turned off well before this change and it remains off for the time being, according to MS. That's why I don't see thumbnails for all files.


There is a group policy: IT Admins - Use OneDrive policies to control sync settings - SharePoint in Microsoft 365

I tried setting that (to disabled), unlinking this pc via OneDrive, rebooting and then signing into OneDrive again, but that keeps the new options for Files On Demand. It doesn't turn it off, nor does it prevent OneDrive from thumbnailing everything.

As a last resort, I can try checking my own devices and go through the registry settings for OneDrive (not the policies) and see how OneDrive knows Files On Demand was turned off in the past.

Hope this enlightens people in a similar situation.