AIPerception ignores placed actor in world

I implemented a inventory system similar to the one described in this UE4 tutorial UMG UI Inventory: Project Overview | 01 | v4.8 Tutorial Series | Unreal Engine - YouTube
If a Item is picked up, it becomes hidden in game and collision is disabled. The problem is the AIPerception system still “sees” the items in the world. If I drop the Item back in the world, the actor gets a new location and is visible again collision is also enabled. The second problem here is, the AIPerception System doesn’t notice the new location. Can somebody help me with this problem?