Bug report:

[Nianniane]

Describe the bug

The spring bone group cannot save bones in certain situations

To Reproduce

Steps to reproduce the behavior:

1. Create a VRM humanoid
2. Copy a bone in edit mode
3. Create a group in the spring bone group and add the copied bones to it.
4. Save the file, the group's bone disappears.
5. Repeat the above operation, but do not save, switch to object mode, the group's bones disappear

Expected behavior

In any mode, the bones in the spring bone group should be able to save normally.

Screenshots

If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information)

• OS: windows 10
• Blender 4.3
• Addon Version 2.3 and 2.31

Additional context

Only the copied bones will trigger this BUG. If you add bones to the spring bone group in pose mode or object mode, you can save the bones normally,maybe.