Prefabs (drag & drop into scene) giving NullReference

I’ve got a problem where a fairly significant amount of prefabs in my Asset library appear to have become corrupted. Drag and drop them into the scene, I get the ‘invalid’ cursor and this message in the console

“NullReferenceException: Object reference not set to an instance of an object
UnityEditor.SpriteUtility.GetSpritesFromDraggedObjects () (at C:/BuildAgent/work/d3d49558e4d408f4/Editor/Mono/Sprites/SpriteUtility.cs:113)”

The inspector is also blank for the prefab.
These prefabs have no scripts attached; they are quite literally just model, material + appropriate colliers & layer/tag information.

I am also suffering from this, however it is only when I create a cube in unity. Any imports as prefabs are ok.

Help on this would be nice.