I’m currently working with a Character Creator 4 (CC4) model exported for use in Three.js, and I’ve encountered an issue related to bone transformations.

When rotating certain bones in Three.js (for example during animation or procedural control), the mesh appears to stretch or deform incorrectly, as if the bone scaling or skinning is not behaving as expected. This results in unnatural elongation of limbs or distorted geometry.

Here are some additional details:
The character is exported from CC4 (FBX/GLB format)

Imported into Three.js using standard loaders (e.g., GLTFLoader)

The issue occurs specifically during bone rotation (not translation)

No intentional scaling is applied in my code
I suspect this might be related to how CC4 handles bone scaling, skin weights, or possibly non-uniform scaling baked into the rig.

Could you please advise:
Is this a known issue when using CC4 characters outside of Reallusion tools?

Are there recommended export settings to avoid bone stretching in external engines like Three.js?

Should bone scaling be reset or removed before export?

Is there a preferred workflow (e.g., via iClone, Blender cleanup, etc.) to ensure correct deformation?

Any guidance or best practices would be greatly appreciated.

Thank you in advance for your help!

Best regards,
Leslie