skinmesh is different between MAX and Unity

As the picture shows, the screenshot is playing idle animation. In MAX, the character chest is right. After import to Unity,the vertices weight is wrong… I’m trying to Reset Xform,rebuild CS,rename and re-import,but still like this…almost 30+ characters imported, but only this one like this, i don’t know why…

Unity 5
Max2010
Bone affect limit:4


Pretty low poly character - so most destructible edits aren’t going to be terrible to re-do if they don’t work.

Save skin data, delete skin modifier, collapse stack to editable poly/mesh, apply new skin modifier, load saved skin data, export. See if that works.
If not - collapse entire modifier stack with skin modifier, apply new skin modifier, check vertex weights, make sure bone influence in max is set to 4 only. Edit if needed, export.
If that doesn’t work. delete the skin modifier, apply a new skin modifier, set bone influences in max to 4 and re-skin.
That should work if nothing above helps.
It’s an odd anomaly since you have other characters that work fine - assuming you used the same workflow as before.