What does some bones location get set to 0,0,0 while importing animation from blender?

what does some bones location get set to 0,0,0 while importing animation from blender? imported bone transformation in different from original this is the error i’m getting while importing the animation from blender. is this UE4 issuse or blender. I tried changing the bones transformation in blender little bit but it do not worked. please anyone help me.