Hi Possa,
Since image and video thumbnails are displaying normally, Windows appears to be generating thumbnails correctly. The issue may be limited to folder preview thumbnails in File Explorer.
Please open File Explorer Options > View tab and make sure Always show icons, never thumbnails is unchecked. Then you can follow these checking steps:
- In File Explorer, switch the folder view to Medium, Large, or Extra Large icons, as folder previews are not shown in some view modes.
- Right-click an affected folder > Properties > Customize, then set Optimize this folder for: Pictures and apply the change.
- If the issue affects all folders, open File Explorer Options and select Restore Defaults on both the General and View tabs.
If the problem continues, please let me know whether it affects all folders or only specific ones, and whether it started after a recent Windows update or system change. Feel free to ask me by clicking "Add Comment" or "Add Answer" if you cannot add comment so your response will be visible. Thanks for your effort.
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