When doing some of the puzzles i have found that the balls dont roll ba…

When doing some of the puzzles i have found that the balls dont roll back as much as they should when collapsing them. Puzzle 1-12 for example. I have watched it on You tube and the spheres dont react that way when i do it?
Can anyone help me with this as it is very frustrating as this has happened on multiple puzzles. please and thanks