It was already off since I was using the Camera Imager override in the viewport. I tried with the own camera Imager settings but the result is still the same.
You can see all my CM settings in this screenshot, do I miss something ?
First one is Viewport Render.
Second is Final Render.
We can see that Octane viewport display right and wrong result whether it's a preview or a final render.
I've totally missed that, you're right. So a warning / splash screen at first launch could be a solution.I'll ask if it's possible to set the Display to none by default. We need to consider a user may have the standard Blender version installed already, so changing its configuration file could be a bad idea.