3D Text only shows Transformation Properties, but not Material Properties

I am on Dimension 3.4.5 on a MacBook Air M1 (16GB), Monterey

I have a 3D Text object that reads "PatroNetX", where "PatroNet" is just the standard white material, and for the "X", I added the red Substance Material called "Smooth Silk".

When I export this as a glTF scene, everything look great, but 80% of the size of the glTF scene is made up of the rough texture for the silk material.

I wanted to replace it with just a red color, no texture, but when I click on the "X" in Dimension, and select Material in the Actions panel, then select the material for "Face" above in the list of materials for the letter "X", I don't see any properties for this material, even though in a number of tutorials I have watched, they are clearly there, on the right, where I only see properties for transformations.

What am I doing wrong?