Roughness texture isn’t listed in the Textures section. This seems like a bug to me?
This makes it difficult to QA glTF files, since it looks like no roughness texture was supplied in the material.
Also I can’t “solo” the roughness easily on the model, as I can with Albedo, Metalness, Occlusion, etc. I can if I drill down to the Debug option, but that’s less convenient.
If I choose the ORM texture in the Scene Explorer, then the roughness is clearly visible in the green channel:
And it does appear properly in Debug mode: