ik spline is unstable with degree 2 curve

[turboPP39M]

Hi. I keep searched this problem in forums but can't found a similar problem, so I'm posting it.

As the title says, IK spline is unstable with a degree 2 curve + more than 18 joints when stretch setting applied. degree 3 curve or fewer than 18 joints are fine. I tested this in Maya 2018 and 2022.5 and both are same.

Steps to make this problem:

1. Make a joint chain with more than 18 joints.
2. Create an IK spline with auto-create/simplify.
3. Rebuild spline curve with degree 2.
   • I also tried delete IK handle then rebuild curve and made IK spline again, but no difference.
4. Apply stretch setting.

Here is a picture of my stretch setting. It's simple. I put the value that stretched curve length / original curve length * default joint translate X into joint translate X. I tried not translate X but scale X, there is no difference