Are you still having this problem ?
Likely is due to game sync issue. Try the item again, try another item, visit madlen. Often waiting or restarting will resync game. Check this thread for more info: Post in thread 'Item already used???' https://www.airportcitygame.com/threads/item-already-used.40364/post-535118Are you still having this problem ?
It just started for me, unable to do a launch
just keep trying to use item untill it registers thats what i doUnfortunately still continues, doing all that was suggested.
Was able to add one item then the message appears again.
Bad thing about it each time I try to add something, I lose it so of course I am only trying to use liquid fuel or small fuel tank. Not about to try PEB
Can’t believe I am the only one having this problem but certainly appears so.