Jitter when moving the rig away from world origin

Assuming the RigBuilder is initialized on start when the rig is at (0,0,0), after moving the rig for example 500 units away from the origin (500,0,0) very noticeable jitter appears on the animated rig:

https://imgur.com/a/WLTxvlZ

After rebuilding the rig (via the context menu, not clear on video due to poor quality) it fixes itself.

Notes:
- it uses Generic avatar
- it doesn't matter if the rig is animated via the nested animator or the main animator.
- Update Mode on the rig animator: Animate Physics

If it's going to help I can provide the repro project. I suspect my rigging setup is somewhat unconventional as in I'm constraining the whole bone hierarchy (hands' root) to the animated handler (also a part of the rig).

Ok, through trial and error, I figured out that this caused by the Additive layer that just plays the idle animation that controls the weapon position pivot. If I put its weight to 0 it resolves the jittering.
Is it expected that there're some problems with Additive layers or I'm just misunderstanding something about how they should work?

Another update: removing the keys for the x and y axes in my idle animation (only z axis was updated anyway) resolved the issue completely.
This seems similar to another Constraint issue (I'm using Multi-Parent) posted somewhere on this forum where unticking (or rather ticking, I don't remember) some Constrained axes also had some positive effect.

Another (and I hope the final) update: removing the unused axis keys from the idle animation didn't actually help. What helped is to call RigBuilder.Build() on the next frame after starting the game like this:

private void Start()
{
    StartCoroutine(ResetRig());
}

IEnumerator ResetRig()
{   
    yield return null;

    _rigBuilder.Build();
}

Seems like a bug overall.