Stabilized bones in Animation

Hello Everyone,

I am currently working on a Proof of Concept for animations and I got stuck on an issue 2 days ago and I am struggling with it since.
Maybe one of you already resolved this or came accross and found a better way to do it.

As you can see in this first video, in 3DS Max I stabilized the upper arms and head bones so the mouvement from the bottom part of the character doesn’t interfer with the arms and head.

After exporting to fbx and importing it to unreal engine 4.17, the bones are not stabilized at all. They just move around with the rest of the body which is really annoying and not really the result I want to achieve. It looks like the frame for these bones are skipped or something. If I import the FBX back in 3DS max, the bones are still stabilized so I can’t put my hand on what I am missing…

Anyone knows what’s up and / or knows a way to fixe it /solve it using another method?

Thanks in advance