Sealed Lock Doesn't Work?

I'm fairly certain that the dialogue box asking if you're sure is something that just comes up any time an item is marked as untradeable and does nothing but pass the instruction to drop, which will then be blocked by your seal. I remember trying to drop the Mind of Maple pendant without any success, and I think something similar happened there.

I'm not sure enough on this one to say that I wouldn't like to see screenshot evidence as well, though.