There appears to be a bug in Octane Blender when one is using the Eevee rendering engine with the following node set up to replace background environment lighting (similar to what Octane’s environment nodes do with Rendered and Visible environments).
The node setup to replace background environment works in the normal non Octane Blender builds but fails in Octane version. Interestingly, the node set up in the Octane Blender build does work with Cycles.
See attached screen shot and blend.