Exported ico files not behaving properly

[meetdilip]

Hi admin. I got this above big image through Blender. Then I made it 256x256 (this time), opened in GIMP and exported it as folder.ico

Now I used that particular ICO file through right click > properties >customise > change icon

Now I selected the ICO output from GIMP. It should look like a normal icon, but it got stretched across the Y axis, as seen below