Hi I'm fairly new to houdini would love some help. I have an fbx model that I've imported into houdini, added a shatter effect. Works great but the classic houdini shader that I added to the fbx at the geo level doesn't seem to be working (e.g I made the shader red but the model stays grey. I'm able to turn a sphere red in a different geo network). Is there a different process to add a shader to an fbx import?

New users are often confused that the viewport doesn't always look like the render. If the render is good, you're okay.

Grey geometry often means the mesh is packed. This is kind of like an on-the-fly ZIP file version of your geometry. The problem is, the material assignment is inside the ZIP, thus the viewport can't access the attribute to accurately apply the material.

Try dropping down an Unpack node at the end of your chain.