Skinning Editor Bones Disappear,Bones disappeared from Sprite Editor after Exiting Unity

On the left, in the scene you can see the assembled character using Bones. On the Right is the Sprite Editor - the bones are gone. They are not on the spritesheet or in the list. But the Geometry is still acting as if they are there. I cannot add any more bones or edit bones.

I spent hours working on this and assembling the character [as you can see, pretty complicated] and I'm worried that even if I can start animating, I wont be able to add anything to the character later. The bones disappeared after I exited Unity yesterday, came back Today to find it this way.

The gameobject is using Sprite Skin and IK Manager, from 2D Animation / IK packages.

Is there any way to recover or prevent this from happening if I redo?