Elf cannon disappears after being stored? Help.

I thought this happened to me too the other day, it took me about 30 mins to find it. When you click edit then click the box for your inventory scroll through the items, it will be in there. I couldn't find it in any of the section boxes (buildings/nature/decorations) etc. it might not have its own category that's why it's just in the initial inventory. Good luck!