Jean-Sebastien Perron

Found the solution, it was simply to add a SOP Name node and creating a name for every material in the .obj.
Then these names now appear in the Solaris LOP Material Linker.
Don't forget to add "name" to Path Attributes.

I imported a .obj model
That model has only 1 mesh with 3 separate material.
Each material attach to different set of polygons.
Material are : planks, plank_top and posts (they are actually called A, B and C)

I tried all the tutorials and techniques and they are not working.
In the /stage I can never see my 3 material/polygon selection

I tried with color and tried with group.
These two techniques are working themselves, but I never see them in my material linker in /stage.
I selected the right @shop_materialpath=/mat/C
so that part is working, but they never appear in the material linker.

I use a scene import LOP, I even tried with a SOP Import LOP but the size and position are wrong.
Anyway, none of them allow me to select group or color or any attribute.

Please don't tell me to use another format.
Don't tell me to split export my model to file.

Thank you very much, but that just proves that server activation is a dead end.
I am returning to Blender, no more wasting my time with proprietary software.