I have it turned on in preferences, but doesn’t seem to be working between scenes. Works fine between panels, but I need it to work between shots/scenes.
I can’t find anything about this in the forums for SBP.
Any ideas?
You could create an extra panel in the scene that contains your references images and copy over the drawing to the scene that needs it. Then delete the extra panel from the reference scene as a workaround.
Thanks, but that creates an unnecessary extra step. I’m looking for a fix, not a workaround. I’m trying to use this software because of these sorts of advantages. If I’m going to copy and paste in place of the onion skin, I may as well be using Photoshop.
Thank you for taking the time to respond, though. 
Onion Skin is working…here’s why it didn’t:
I have TIFF images imported for tracing. When the TIFF image has its onion skin marker turned on, it fills the background of the next scene/shot.
Sort of embarrassingly obvious, now that I think about it. :-0
thanks for posting solution to this. Had the same problem.
do you know as well how to change the aspect ration frame on panels from the default grey?