Hello! I'm 3d max 2016 user. Today I found a very nasty bug. Sketchfab losing shoothing group iformation on meshes with morph modificators.
3d max vievport - http://joxi.ru/zANb6kIlGxoxA9.jpg
and sketchfab viev - http://joxi.ru/12Mb5pI4NXoLAJ.jpg
Smoothing info saved with exporting. But sketchfab make it like its in single smoothing group. So models looks corrupted on hard edges with normalmapping. (*yep, body hame morphs for inhaling imitation. gun and compass have the correct origin smoothing groups)
I very much hope that you are able to fix the problem. Or suggest how to solve it.