FBT Behavior when changing state Standing <-> Crouching


I’m curently making an avatar, i did it first in SDK 2.0 because i was used to it.

I’ve decided to put it in 3.0, Everything looks fine until i found a weird behavior when i’m in FBT…
It’s looks like the chest bone moving when my avatar are at the “crouching” state :

A GIF for show you how it’s looks : https://gyazo.com/55138499ad164e56ab9d0a25acb1422b

I tried different settings, Default LocomotionLayer, Custom one, the Lower body options in the avatar descriptor, veyfing the Armature…

My only fix is in the LocomotionLayer to change the height value for pass to crouch, but obviously that broke the avatar for Half Body VR and Desktop…

Any ideas what that cause that and how can i fix that ?

EDIT : I just saw a friend with 3.0 avatar have the same bug (less important moving chest than me) and an other friend confirmed with his avatar aswell… So he gonna give a try with an Y-bot avatar soon

Thanks you~~