Mecanim Humanoid not retargeting properly?

Hello, and thank you for reading this

I am currently trying to reuse an animation on a list of different humanoid models, using Mecanim's retargeting system, however I am getting some weird results. As you see below, the two models have the same pose, and the rig structure is the same. The animation you can see in the video looks fine on the original (left), but the hands are sliding really badly on the new model (right). I have set everything as humanoid, with avatar definitions set to "Create from this model", and the animation clip settings can be seen in the other picture.

I have also tried with some characters and animations directly from mixamo, and have noticed they are not retargeting properly either, so I'm assuming I'm missing something in the process. I have followed the documentation tutorials for this process. Both models have an Animator component, with the same Animation Controller assigned, and their own avatar definitions. Any help would be appreciated