No problem.
I did some more tests and was able to reproduce the issue. As you suspected, I was able to confirm that it has to do with a bug in the exporter itself (rather than specific settings) that affects Max 2014 and 2015, but apparently not Max 2016 or 2017.
I'm going to pass a sample and my notes onto programming. With any luck they'll be able to find the source of the bug and add a fix to a later release of the exporter. For now, I'd recommend sticking to smoothing groups.
As a side note, and on the topic of normals, I noticed that in an old post you asked about using tangent space normal maps. If you aren't already aware, Vizard 5 added a new shader (vizfx) which supports them. I've attached a zip with some sample files (max, osgb, script, osg preset).
You can find more info on the shader here:
http://docs.worldviz.com/vizard/Shaders_3DS_Max.htm