After saving the selection state of the vertices to the selection group, the selection state of the vertices will be lost when the project is saved.

[misaki-eymard]

Description:
Spine allows you to save the selection state of vertices such as mesh attachments and clipping attachments in the selection group, but in versions of Spine 4.0 and later, these selection states are lost when the Spine project is saved. (In Spine 3.8, it has been confirmed that the selection state of vertices is properly saved even after the Spine project is saved).

Expected behavior:
Even if you save the Spine project, the contents of the selection group that has been saved once will be maintained.

Steps to reproduce:

1. Open spineboy-pro.spine in Spine 4.2.36.
2. Select the head mesh attachment for Spineboy and select multiple vertices as desired.
3. Press Ctrl + 1 to save the selection state.
4. Unselect the vertices, then press 1 to confirm that you can select the vertices that were previously saved.
5. Make changes to the Spine project by switching active animations, etc., and then press Ctrl + S to save.
6. If you press 1 again, you will see that the entire head mesh attachment is selected, and the vertices that should have been selected in step 4 are not selected.

The versions of Spine that can reproduce this issue:
Spine 4.0, 4.1, and 4.2.

This issue was reported in the following thread on the forum:
https://esotericsoftware.com/forum/d/27110-%E4%B8%80%E4%BA%9B%E5%9C%A8%E4%BD%BF%E7%94%A8%E4%B8%AD%E9%81%87%E5%88%B0%E7%9A%84%E9%97%AE%E9%A2%98%E4%B8%8Ebug