ConvexDecomposition | slicing concave polygons into convex polygons | 3D Animation library

I'm using bulletsharp (C# wrapper of bullet physics) to do some collision detection. Everything went fine until i tried to change the collision shape of an existing rigid body from box to compound at runtime. I'm doing this to simulate the collision again with a higher accuracy. The problem is: collision of compound shapes is not detected.

Scenario:

• DicreteDynamicsWorld containing some RigidBody with BoxShape
• Collision of two kinematic RigidBody with BoxShape happens (and is detected)
• Change the shapes of these two RigidBody to CompoundShape using the HACD algorithm for convex decomposition
• Remove RigidBody from DicreteDynamicsWorld
• RigidBody.CollisionShape = CompoundShape
• Set Position using RigidBody.MotionState.WorldTransform
• Add RigidBody to DicreteDynamicsWorld
• Undo the movement which caused the collision (one object doesn't contain the other)
• Repeat the movement
• Collision is not detected

Remarks:

• Changing the CollisionShape from BoxShape to CompoundShape was successful (correct CollisionShape and correct position)
• For collision detection i'm using DicreteDynamicsWorld.Dispatcher.NumManifolds > 0 after a DicreteDynamicsWorld.StepSimulation(...)

Some code snippets as requested:

If you need something particular, please tell me. My solution is too big and too complexe to post the complete code...

RigidBody creation: