Super Services 3 issue

I’ve done every city design challenge during Super Services 3. After each challenge, all items I use in my design whether it’s Services, Parks, Entertainment, etc always returns to city inventory.

but I bought a Saltwater treatment plant from the Maxis Shop and used it in a city design challenge and it did not. 

I saw where I was able to buy another Saltwater treatment plant from the Maxis Shop and used it in another design. It also didn’t return to my inventory after the challenge.

username: hackerhog