Incomplete Figure disappearance
I kept hold of the figure I had, but it appeared to have vanished at some point during G24. It would be interesting to figure out when exactly it's removed from the inventory and add it to this page.
There's a section during the Two Knots quest (the second time you talk to Eirawen) where you show her the figure and the two of you discuss over it and she mentions finding others in the lab at Tara. I think you either lose it right there, or if not then right after completing the Two Knots quest altogether (when you burn the festival puppet at the end).