Create IK on gltf hand model

I am trying to use inverse kinematics on a hand model.
I have downloaded a pre-rigged model from github.
I modify the model in Blender, adding target-bones and inverse kinematics constraints, and everything works perfectly from the Blender side.
However, when I export as glb and try to apply the IK using the CCDIKSolver in three.js, everything breaks, with the bones starting to jitter randomly.

Do you know what the issue might be?
Can anyone demonstrate an example for this case?