I didn't need to Restart, camera went back to previous view and the ball was there already. So I could try again.
This is how I did it consistently:
1. Hold the ball with magnet
2. Once ball is above actuator (the one which triggers immediately, with one force setting), release magnet and quickly click on actuator
3. Ball will get some force forward, not enough to get to the end of level, but enough to trigger camera movement.
4. Ball falls back, camera goes back to previous point and you can try again
I think it's because I was clicking actuator right after releasing magnet and the ball might either be still a bit "stuck" to the magnet, or maybe it's a bit in the air (not touching actuator fully), and doesn't get full force applied.
In the end I managed to get past it by being a bit more patient with 2nd click on actuator.