I had several items that I purchased from a seasonal selection and they suddenly disappeared from the..

Check to make sure they're not hiding behind large objects/buildings. I've also experienced occasions where I bought something, placed them, moved things around, and the next day it was like that none of that ever happened. Somehow my game did not save as it should; some glitch. You can try to contact customer support through the "help" button in the game settings and tell them your game user ID and the items that are missing and see what they can determine on their end.