I've had this problem before but don't remember the fix. I have a "floor" that's a static mesh. Like a sweep for photos. I have a cloner with a capsule. The capsules drop to the floor when I run the timeline in order to get the random pile of pills on the floor. They're not hitting the floor. They're floating just a bit above the floor. They cloner and the capsules are set as moving mesh. I'm stumped. I've moved the dynamics tag to the cloner and the capsule and the result is the same. I've used this technique many times - just don't know what's going on now.