Thanks, I'm still not completely sure what I did wrong, but I found that deleting the problem layer and redrawing it solved the problem.

I just got Moho 12 (previously I had 9), and so I decided to re-rig my character with smartbones. This was all fine for the torso, until I reached the waist area. I went in to do the action for the STOMACH bone, I could move the points and all while in the action, but when I go back to the main time...