Yeah it’s the same as the guys above for me, it seems to work fine.
I duplicate M_Glass_RT_Material, add a Thin Translucent Material node with a Constant3Vector plugged in for colour and change shading model to Thin Translucent too.
If I then convert Constant3Vector to a parameter and instance this material, I can change the colour and it updates isntantly in both the viewport and material preview.
Have you applied the changes to the master material you created and saved it? Maybe it just needs to recompile?