Repro: Setup a Standard Shader with a texture in the Primary Diffuse and Secondary "Detail Diffuse" slots. Submit this material to version control. Create a fresh clone of the project and open this for the first time as a new project in Unity.

Note: The secondary diffuse will not be visible in the scene view, game view or material preview. Tweaking any value on the shader will cause it to suddenly pop back.

Expected: Should reflect what the shader looks like at all times.