Rig Builder bug with retargeted humanoid rigs

I have downloaded Robot Kyle as my target model. Its animations are from Mixamo with the Y-bot as target. Whenever I have a rig builder component that has a rig with constraints attached (doesn't even have to be an active rig). There is a strange offset and unwanted behavior. The more of constraint components I set under the rig, the more offset comes from it.

I am using Unity 2020.2.3f1, with Animation Rigging Package 1.0.3.
Is this a known bug? Can anything be done?

I have a very similar problem posted here: https://discussions.unity.com/t/827864

Looking for help :(