Bug Animation Rigging doesnt work for some animations

Hey!
I am using Unity's Animation Rigging Package (Unity 2020.1.7 Animation Rigging Package 0.3.4) in order to edit some animations, However, using a Two Bone IK Constraint only works during some of the animations for my character.

In this video I have 2 IK Constarints active, that are altering the hand position. During the running animation they work perfectly fine, however, during the idle the right arm is going all over the place.
Why is this this happening and how can I fix it?

The animations I am using here are from 2 different Asset store packages and therefore use different Avatars. However, some other animations that are also using a different Avatar, for example the run animation for fine.
In addition to that problem, I cannot bake the Constraints into the skeleton. This option is greyed out.