I think I've reported this bug in another game. It was mentioned in The New Zork Times, with a promise that future games would not have it:
>PUT KNAPSACK IN BLACK BOX
Done.
>PUT BLACK BOX IN KNAPSACK
Done.
>FIND KNAPSACK
You can't see any knapsack here!
>FIND BLACK BOX
You can't see any black box here!
I think I've reported this bug in another game. It was mentioned in The New Zork Times, with a promise that future games would not have it: