At the new castle near Old Fields North of Stary. There was loot under the floor, or on top of the ceiling depending on your position :). Tried to access loot through floor but couldn't.

Went there again and loot was under the floors again.

Loot was under the floors at the castle at Black Mountain, Just SW of NEAF. There was one item on top of the floor at this location. {F28482}