Skull Key Missing.

[Orangatuan]

I've played through a large hard custom game as an assassin, got to floor 10, killed the jelly monster boss, I picked up most of his loot, as I tried to pick up the Skull key I got an "Your inventory is full" message and the key disappeared. I've since made some space in my inventory but there is no Skull key, I've cleared out the rest of the floor, and have encountered no Skull key, I even spent 30 minutes slowly inspecting every room.

Images of map, chest room and inventory.
http://imgur.com/a/GHnup

[DJ_Link]

Hey Orangatuan,
Sorry to hear about that. That is really strange, first time hearing about this, the closest I read was someone selling the key to shopkeeper and not being able to buy it back.
There is no mechanism in place that would delete items when you can't pick them, if you pick a lot of stuff and try to catch stuff you'll notice they will stay in place. That said, games are not without bugs so this may be a cause of a combinations of certain things which I'm not aware of. Tell me something, was it only the key on that tile, or could you see more things there? Just trying to rule out things to possibly find this bug.
Unfortunately, if the key is gone there is no way to actually open the chest and trigger the end game sequence, and I'm deeply sorry about that :(

[Orangatuan]

It was the last item on the tile. No worries, I've started a new game now, so I just thought you should know.