How to reproduce:
1. Open the attached project
2. Open scene
3. Select sprite from Assets folder
4. Drag it onto the plane in the scene.
5. Make sure the cursor passes through some empty space in the scene before hovering over the plane.
6. Release the sprite to apply it as a texture for the plane.

Actual: texture is applied to the plane but sprite's preview persists in the scene
Expected: Texture is applied and sprite's preview disappears
Note: In 5.4 after drag and drop nothing happens, one needs to start moving the scene view and only then texture is applied

Not reproducible: Unity 5.5