I have a slim and tall human and I want to use it's animation for a fat and short human. but the bone stretched and My character deformed. both character use their avatar and the bones in change avatar assign correctly.
I retarget character as same as tutorials in web that don't have a complex in instructions. and don't have any error in avatar change part in assigning bones. test multiple animation. test key frames and see value in key frame is constant. for example if your y position be 2 for your shoulder in key frame number 10. in short character characters must be stretched in y. and I think unity doesn't retarget different body correctly. mixamo character have similar body shape and in that situation we don't have problem.