Is it just me, or Blender 3 doesn’t store the scene thumbnail?
I’m non Windows 10, and I’m using the latest official Blender 3 release.
In my case it happened when while saving the file, there were no 3d viewport in the whole UI. I had the image editor opened after the render was finished and saved at that moment.
I switched back to 3d viewport and tsaved, then the thumbnail was created…