Render Materials not Saving in WebGl HTML file

Long story short:

I’m using Matrix 7.5 to build the 3dm file, then opening in Rhino, adding render, then saving HTML with WebGl.
But my html is coming up as a plain white build, no render materials attached?

I’m thinking I need to change the external resource to the Matrix75 folder but have no idea how. Any suggestions?

Hi Chelseya - How are you saving, exactly?