I noticed since upgrading to H19 that the Principled Shader no longer shows the basecolor value in the Solaris GL viewport. I went back to check and this does work in 18.5, but now with the simplest possible setup I just get a greyscale result in the viewport:

Plugging in a constant doesn't help:

But if I promote and expose the parameter it does work:


I assume it's an issue with the GL tags on the parameter but I'm curious if there's a reason this behavior changed in H19.

It's a tossup which other GL shading values are read correctly -- metalness works, transparency doesn't, etc.

After I unchecked "Only copy specified prototype primitives" option in instancer node, viewport started showing colors.

did you find any other solution to this other than promote and expose the parameter?

Don't use the principled shader in Solaris, it has to be converted to a usd preview shader for GL so you will always be relying on that conversion.