More particular, exporting the results of Data Transfer modifier. From 2.77 or higher. So far custom normals do not have any effect for me, no matter the format (fbx, dae, 3ds, obj, tried them all).
did you already check this?
http://blender.stackexchange.com/questions/46545/why-cant-the-data-transfer-modifier-be-applied
No I havent checked that before. Simply because I had no idea it will require adding extra datablock to the mesh. Plus most of the threads on this topic were either dated or inconclusive, so I asked here. Thank you, it worked!