Hello, I'm using redshift in solaris for the first time and I'm having an anoying behaviour. I have my scene already setup and perfectly looking in the viewport IPR but when I render to a file it renders without any material. This also happens when I close Houdini and re open the file, the first viewport IPR render appears without materials, I have to go to OBJ context, launch a rendeview from there and then I can comeback to solaris and it back to render with all materials. Maybe I'm doing something wrong, could some body give me a hint on where could be the problem?

Bumped into the similar situation. It's most likely the same reason.
If you copy over the RS materials into LOPs, you have to add the RS usd output VOP to it.
Just create a new RS LOPs material to see what's needed.