It seems Select
does prevent attachments from ghosting. In the code I see the comment:
Don't ghost attachments that are not selectable.
So it was done on purpose, I believe because unchecking Select
is often done for background images, and ghosting those can make ghosting unusable. However, background images are better placed in a different skeleton, so maybe we should have Select
not affect ghosting.
You can't ghost only a specific attachment, but you can ghost only the attachments for a specific bone:
Ghosting - Spine User Guide: Selection