When your model is not displayed correctly, the following could be the reason for it.
Make sure the VRM model data is correctly set up.
We've seen many models with their hip bone being around the feet.
(This is common in models just converted from MMD)
If unintended penetration or trembling occurs with swingable objects,
the case could be due to Pose Freeze not executed during VRM Export
or RootBone setting for VRMSpringBone being configured inproperly.
If the structure configuration mentioned above is correct but the model is still not displayed correctly, it could be due to malfunction of FastSpringBone.
Try turning off the FastSpringBone feature.
It would help us a lot if you could report the issue to VirtualCast Steam Community in either case, the method mentioned in the article solved the issue or not.