PBCN saves the element it's cloning.

@TlccXtreme (View Post)
Have you turned Newtonian gravity on in simulation options? Have you heated or cooled the GPMP (the gravity generated depends on the temperature)? And try pressing Ctrl+G - the gravity field is now hidden by default.

Also, this might have been better in the feedback thread... https://powdertoy.co.uk/Discussions/Thread/View.html?Thread=8815