diamondmonster Thanks for sending the Spine project files! This should probably work as expected, not a bug. The setup is a bit different for the two Spine projects you sent us:
One is not bound to any bones and one is bound to the bone and bone2 bones. The position of the vertex is determined by a combination of both the bone transform which affect the vertex and the vertex deformation, but since the bound bones are different, I suspect that this will result in different reference positions and the shapes will not align as you have posted.
Therefore, aligning the bound bones of these two mesh attachments should solve the problem.
This could be done by deleting bone and bone2 as you wrote in your email, but to begin with it is better to avoid using the mesh deformation key as much as possible. This is explained in detail in the user guide, which we encourage you to read: https://zh.esotericsoftware.com/spine-keys#%E5%8F%98%E5%BD%A2%E5%85%B3%E9%94%AE%E5%B8%A7
In conclusion, in both Spine projects, it would be better to bind the mesh attachment to one or more bones and deform and animate those bones.
If you have any questions, please do not hesitate to ask us!
