Texture preview in Inspector not displaying alpha and mipmaps anymore?

Hi! When selecting a Texture in your Project you get it's preview in the Inspector, but you are supposed to also be able to swap between its RGB and Alpha channels by clicking a button on the Preview's image name and even to "zoom" through its mip levels. I can't do it anymore, I'm only seeing the texture preview but can't figure out how to see its alpha anymore : /

Any help will be much appreciated. D