I had just added the Ruby ring scheme to my library. I then looked through my craft and construction library and my two golem schemes (cotton and wood) are gone. Are they supposed to disappear after a certain amount of uses? I remember I used the wood golem scheme twice. I do not remember how many times I used the cotton scheme. 

Does anyone else have this problem? Not sure if this is a bug...

Unique craftable items which you already own do not show in the Craft & Construction tab anymore. It was suggested here. Lower level structures are still displayed but will be removed too soon.

Phew... I was panicing there! Thanks for clarifying, Angel!