Export Animation from 3ds max to Unity

I’m in trouble with 3dx max export .fbx with animation and import to Unity.
I have a charactor with rigging and skinning.when import into default Unity 5 or Unity 2018 Scene, I find a problem, The charactor was backface to camera. but the charactor’s rotation is correct (0, 0, 0). what is the problem and how to slove it.

Which axis, your character is facing towards in 3ds max?