Physics 2 ball escapes box

How do I…

Fix an issue where the “atoms” escape “the box” in physics 2

Original game

This is a game where atoms bounce around a box. The player can click on them to split them apart and earn points.

What is the expected result

the atoms stay in the box and bounce around

What is the actual result

I have been hearing from other players that the atoms, but I can’t recreate the issue myself. Players also told me that it’s an easy fix.

Related screenshots

Project files (optional)