No prefab previews in asset window

As title suggests, there is no prefab previews at all. Heres the submitted bug report: https://fogbugz.unity3d.com/default.asp?1370033

7542646--931888--no prefab2.png

Same issue as here probably: https://forum.unity.com/threads/prefab-meshes-material-thumbnails-in-project-view-are-shown-as-empty-grey-box.1139461