Alpha weird behaviour in transmissive material with roughness map

[1k0]

Hello everybody,

I noticed a weird behaviour when rendering a mesh using Arnold standard surface with transmissive + a bitmap plugged in the roughness slot.
In the following scene there is a box with 2 meshes, 1 with an opaque et 1 with a transparent material. The transparent one affects the alpha of the opaque material as soon as I plug a texture in the roughness slot. The texture is a simple black and white PNG file.

The actual fix I found is to play with the Extra roughness option of the transmissive material and set a negative value until the alpha looks correct but this is not a usable solution if we want rough refractions in the mesh.

Did some of you encountered this issue?
3ds max 2020 Arnold 5.0.2.42

[lee_griggs]

Does transmit_aovs help?

[1k0]

Hi Lee!
It's activated in my tests and it doesn't solve the issue.