Mesh is acting strange in animation sequence

I have converted other source to fbx using blender and imported it to UE4

imported data is consisted with Amateur+Mesh in blender

After retargeting every bones, and applied animation

and the result is below.

some parts get abnormally stretched and don`t know why

have checked bone name mapping again, but seems fine

what is the cause of this error and how to fix it?

What happens when you load animation with mesh and skeleton icluded?