So I’m trying to use virtual bones in a very similar way to how they are used in the UE example (Virtual Bones in Unreal Engine | Unreal Engine 5.0 Documentation).
My goal is to have a weapon pose and then still parent the left hand to the gun after applying weapon sway animations. I set up VBs (source: wrist_r, target: gun_r), (source: wrist_r, target: gun_r) and then made some additive animations where I add sway to the hands. Then I use a layered blend per bone in my additive blend space to ignore the virtual bones (so they are not affected by additive animations). Then I use a control rig to set the transforms of the wrist_l and gun_r to the virtual bones.
For some strange reason, the location of the Virtual bones is being preserved correctly, but rotation is still being affected by additive animations. This problem persists whether my additive anims are mesh space or local space.
To show this I used two control rigs to log the initial (local space) transform of the virtual bones and the final transform of the vbs (after applying additive anims). You can see that rotation is changing, meaning the additives are affecting its rotation, even though I am ignoring it in the blendspace).
Here is a video to show whats going on:
EDIT:
I confirmed it is something to do with the AimOffset node specifically because when I apply an additive normally the VBs do not move:
