I was making a multi-directional flying machine and in one circuit I had an observer be pulled by a double piston extender then it would fire the sticky piston multiple times and it is turning to stone now.
I am not sure if it's the observer or if it's that the piston is trying to fire and be pushed at the same time.
I also don't know if it's the same with normal pistons.

ps Sorry here is the world download