It seems like the issue you're experiencing with the path constraint and the vertices positions changing is related to the order in which constraints are applied. When you copy the arm hierarchy and reapply the path constraint, the vertices positions might be affected if the constraint order is not set correctly.
To fix this, you should ensure that the path constraint is applied in the correct order. Constraints are calculated from top to bottom in the constraints node, so you need to move the path constraint to the appropriate position in the list. This ensures that the path constraint is calculated before any other constraints that might affect the vertices positions.
Here are the steps to follow:
- Go to the constraints node in the tree.
- Drag the path constraint to the top of the list or to the correct position where it should be calculated first.
- Reapply the path constraint to the copied arm hierarchy.
For more details on constraint order, you can refer to the Spine User Guide on Constraints.
Additionally, ensure that the vertices are selected and pasted in the same order when copying and pasting. This can also affect the final positions of the vertices.
If you continue to experience issues, you might want to check if the axes are set to "World" instead of "Local" as this can also impact the vertices positions when constraints are applied.
Here is a related discussion that might help: Path Constraint abnormal behavior.
