Why is my sprite disappearing when I make a new material and add the Sprites-Default shader?

When the sprite’s material is set to Sprites-Default, it works fine. However, when I apply that to a new material and add Sprites-Default as a shader, the sprite suddenly vanishes. Why is that? I tried modifying the sorting order of the sprite, thinking it has to do with the rendering order, but no change whatsoever. In addition, the sprite is partially visible when I set the shader to Sprites-Diffuse, so I don’t understand why the original sprite shader is omitted when it comes to making unique materials.

When you say it disappears do you not see anything at all or do you get a blank plane/object? do you have a screenshot/screen capture you can share of the issue?