Blank test project file In Octane Standalone 2025.a beta 1, the TIFF results are as expected (working, no issue whatsoever).
Exporting the Cinema4D project file as ORBX to import in Standalone for testing purposes would be informative. It would double-confirmed the issue is C4D Octane related ...

No problem.

Setting
https://drive.google.com/file/d/1YXcFXu ... eLIT_dSBRK

Result
https://drive.google.com/file/d/1IaRrWQ ... rJuwJ0ulML

Scene
https://drive.google.com/drive/folders/ ... 7aUY-joGJg

Maybe I didn't explain it correctly.
That's what I mean.

Scene Settings #1
https://drive.google.com/uc?id=1eSSiZMPkEqzaZT-9Um7V1FQaSvY03k6i
What I see in Photoshop
https://drive.google.com/uc?id=1M6RN6XVOr9ClNdn5dFLAbffOkClkmTW_

Scene Settings #2
https://drive.google.com/uc?id ...

Win 10
GeForce RTX 4090
RAM 128 Gb
572.60
-
2025.1
Cinema 4d 2025.1

Starting from Octane 2024, It stopped recording Premultiplied Alfa in PSD, PSD and TIF Beauty layer. It writes to PNG from the same file as before.
That is, in PNG I get a file with a transparent background in the right places, if ...