Hi Steve,
Actually you're not alone, many users prefer the Details view for its structured columns but also want to see thumbnails for quick identification of images or videos. Unfortunately, in Windows 11, thumbnails are not supported in Details view. Thumbnails only appear in icon views (Extra Large, Large, Medium, Small) or in Content view. Microsoft has not provided a way to enable thumbnails in Details mode, and there is no official fix or registry tweak to change this behavior.
The reason for this is that Microsoft redesigned File Explorer in Windows 11 with a modern UI framework. In this design, Details view prioritizes metadata columns (Name, Date, Size, Type, etc.) and does not render thumbnail previews. This is consistent with Windows 10 and earlier - thumbnails in Details view have never been officially supported.
I hope you find this piece of information useful to some extent. It's really appreciated of you to accept the answer as a way to share your valuable experience with the community. Thank you :)
Vivian