When I create a new sprite from Assets → Create → Sprites and then select any of the types available, the generated image does not have a preview image, they all look the same:

This used to happen in older versions also, or was it fixed at some point?
I have no idea, i downloaded the build from a link here on the forums… should be the latest one.
In One Column Layout, the icon is the image asset, in this case the image is a white square.
If you switch to Two Column Layout it will show a preview.

I will try that, but i still think this is a bug … i think other asset types all show the correct preview.
Its standard behaviour. In One Column, its an icon in Two Column its a preview of the asset.
So here in One Column view is an image with multiple sprites. The base image has an icon created from the image. The defined sprites don’t show a preview, just icons.

In two column view it shows a preview of the defined sprites

In two column view, at the bottom there is a slider that increases/decreases the size of the preview. Move it all the way to the left and it will look like One Column view. I usually use this to quickly between looking at preview thumbnails to list view.