I haven't found any other reports of this; apologies if it's already been documented. I discovered today that you can cast skepticism on closed doors. The door stays there and there seems to be about a 50% chance of an item spawning under it.
One of my mod's spells uses manipulateobject, the same effect type that Close Encounter uses. It's casted in Template 10. I casted it and two gems spawned. It seems to have a 20% chance or so of spawning a random gem. No other items spawn. Doesn't matter what I cast it on. Methinks manipulateobject accidentally has spawn randomgem in its code somewhere. Or something.