Onion Skinning Issue

I'm having a particular issue with onion skinning that I had not seen before, and I was wondering if any one else had come across it.
When turning on onion skinning, the majority of the character disappears - but not all of it. It looks as though the bounding box of the layer/object selected is obscuring the rest of the character.

Not sure if it's a bug or simply user error. Any feedback is much appreciated!