Thanks Dave,That filler cushion is an odd duck...about 4’ long, 8” wide and stepped on the bottom. I’ll get you a picture this week.
For a replacement, you can buy bed foam and cut a new one. Upholstery shop would do same thing.
I stick mine under the pull out settee, so check there if you haven’t already.
Based on those dimensions I am definitely missing that piece. I have looked under the settee and only the the cushions to convert the settee to a bed are there. I would very much appreciate a picture of that odd duck filler if you wouldn't mind. Thanks again.