I accidentally picked up a slueprint spot (house), and the materials vanished. They don't enter the inventory or fall onto the ground, they vanish. I lost a lot of time and resources in the process.

Completed items still delete items as if it were a blueprint confirmed 0.9.0.780

I tried this earlier, and I was able to move an incomplete blueprint that had an item contributed to it without losing the material. However, I went back in and hovered over the incomplete blueprint and deleted it, and it deleted the item that was in it as well.