Hi, I've been dealing with this same issue over the past week trying to get my normal textures to look right (not flipped) on a non UV'd geo using triplanar projection. I have had some luck in UV'ing the geo and flipping the individual UV islands, but not only does this not make any sense to have to do when using triplanar projection, it's a huge hassle to have to correct.
In researching this it seems that that this is a long standing issue not just with Octane, but with normal mapping (particularly in relation to triplanar mapping) in general across the industry. I came across this article on Medium by Ben Golus that addresses this issue directly: https://medium.com/@bgolus/normal-mappi ... bf39dca05a
In the article he not only explains the reasons why this happens, but provides the code necessary to solve the issue: https://github.com/bgolus/Normal-Mappin ... nar-Shader
The solution is written for Unity, but I'm sure could possibly lend some insight into how this problem could be solved within Octane.
I'm wondering as well, while we wait for a fix, if anyone here has enough familiarity with OSL to try and port over Ben's solution to create an Octane projection node that could be shared with the community.