Guild Wars 2

If your inventory is full you cannot load the Matrix Cube Key. You have to have at least one empty inventory place.

Looks like the logic in the game is: add a new key and then remove the old one. If you do not have a free inventory slot then the the new key gets not added even though the dialog shows that you loaded it (interaction with the loading station).

It should be a proper replace not requiring an additional free inventory slot.

Not a biggie but can be annoying if you made it through the nasty ice room JP, load the key and leave and then see that the loading of ice was not added and you have to do it again while people are waiting that you open the portal to the Steam Ogre.

Unfortunately all MMO’s and other inventory having games do inventory replace like that. Some of them have an additional overload window that pops up telling you your inventory is full and has the additional item in the window so you can take it after you delete something else.
Logic is like this: user clicks consumable, open it (rng if necessary), place it in inventory, delete empty container. The delete happens at the end just in case there’s an issue with something and the rest of the process didn’t complete so you still have the item and can try again.

It is a problem of course, but they probably aren’t going to do anything about it unfortunately.