Hi @MusicMan,
I was able to reproduce the problem with physics.world.setFPS().
See the Pen [Phaser 3] physics FPS &rt; render FPS by Juan Jose Capellan (@jjcapellan) on CodePen.
If the fps of the physical simulation are much higher than the fps of the render, then between rendered frames more things happen than we can see on the screen.
But I guess a callback in the collision should work.
Regards.