Material SOP assignments not working in MtoA

[psyop]

Platform: Win10

Houdini: 18.0.597

HtoA: 5.5.0_r1582e12_houdini-18.0.597

When using Material SOPs to assign different arnold_materialbuilder materials to different prims of a piece of geometry, the resulting exported .ass files do not render properly in MtoA. MtoA complains about not being able to find the materials.

Of course, when the same materials are assigned at the OBJ level, MtoA renders the exported .ass files just fine.

Is this a known bug/limitations of HtoA?

[Stephen.Blair]

Sounds like you didn't export the shaders. It works fine for me.

Check the exported ass file for shader nodes, and check a Detailed Arnold log for the actual export to ASS.

[psyop]

Is there anything else that needs to happen apart from checking the Export Shaders checkbox? Because when the .ass file is loaded onto an aiStandin in Maya and rendered, the following error appears:

/ Error: [ass] line 47: /obj/collate_test/collate_ass/objnet1/RENDER_GEO_FOR_ARNOLD/polygons.shader: unresolved reference to '/mat/shells_flames_arnold_preroll/standard_surface1' //

[Stephen.Blair]

No, there's nothing else to do. That error means the shader was not exported, or somehow has a different name.

Since there's more than one way to do anything in Houdini, perhaps you can upload a simple example that doesn't work?