Lets say there is an Encampement in the trash and I play it via Necromancer, but do not show a gold. ShuffleIt lets the Encampement stay in the trash. I think it should move back into the kingdom.
Sequence as i think it should bed:
Necromancer: Play Card from the trash, turn it face down afterwards.
Encampement gets played, does not see a gold and gets set aside. Necromancer tries to turn it face down but looses track. Encampement gets put back on its pile.