Just updated CH to the CC18 to try out the new physics behaviors. The SAMPLE physics puppet is cool, but as soon as I change ANYTHING in the PDS, the physics cease. I've restarted, refreshed, re-imported the fresh physics puppet; same problem every time.
To recreate this problem:
Download the Physics puppet.
Import into CH.
Open the CH Media > Gathered Media > PhysicsPlayground.psd
Make any change (hide & show a layer.)
Return to CH. It automatically updates the file.
Physics stop working... no gravity. No movement. I can drag some items which collide with SOME items, but not all. Green puppet loses limbs, which eventually return to him.