Yes Lewis is right, actually this goes even further back than V3...
Long story short, there are two long standing issues with normal (& bump) maps in Octane:
1. They depend on UVs. If you mirrored your object, but kept UVs as they are, your normals will be flipped. To fix this you could create a copy of a material with a flipped (inverted green or red channel) normal map and assign it to the flipped part of the mesh. Or you could flip one of the channels of the normal map in your shading network. See this
2. Depending on the camera angle, they might not render correctly. This can be solved (to some extent) by replacing the blue channel with a constant linear value of 1 (or 255 in 8bit) or by reducing the intensity of the normal map in the ImageTexture node. You could also use falloff to reduce intensity of the bump/normal on the edges. See this (apologies for the huge post, I hope those gifs help explain this)