Pivot is incorrect
After loading the model and adding a joint, you might notice that the pivot seems off. This is a Unity feature to make it easier for users to move objects. For Prespective however we do need the original pivot. To change the pivot to use, set the Center button to Pivot. This affects what Unity uses to transform objects. Center uses the center of the object and Pivot uses the original pivot of the object.
Always make sure this is set to Pivot.
Prespective Documentation