This is have to do with the speed that you moving the circlething stuff.
If the speed is very high the construct 2 cant handle the collision checks of an object because it cant make accurate calculations of the position of the object (i remember when i first start with construct 2 and i was trying to reproduce a breakout like game i had the similar issues as yours with the ball and the bat (bat with mouse movement) .
So ,my conclusion is an object with very high movement (in both axis x and y) vs collisions check = 1-0.
Maybe a more experienced member can help you with this. Maybe a different approach of the problem gives the right results .