Hmm, and do you say that this problem only happens in the IPR? It is really weird. Can you please disable the multi-thread scene extraction option in the Octane ROP node to check if it helps? If the problem is still there with the multi-thread option disabled, can you please send me the log file that you get with this option disabled?
I'm trying to figure out what is the object that could be related to this issue because without the scene it is going to be really hard to know what could be the problem.
Computer Graphics Software Developer
Octane plugin development and support: LightWave and Houdini