Unable to convert Texture Type from Advanced to any other

All of my sprites have Texture type - Advanced by default. Whenever I try to change it to Sprite, and click apply, it converts that Texture type back to Advanced. And that’s pretty irritating.
Did anyone else had problem with this?

Bump. I urgently need this. I can’t optimize my game properly because Unity is not seeing my texture as a sprite, and my game is 2D. Please help!