here are a couple of issues I found and the solutions I implemented to fix the issues
first, even with the variable velocity and the polygon collider, the ball still seemed to get stuck. The polygon collider did help a little but it took forever for the ball to reach the top.
So, first thing I did was set the gravity scale to 0. I know this was mentioned as not being a good idea but set to 0 it plays more like arkanoid does.
The second part was to change the random velocity range from 0-0.2f to -0.2 to 0.2 - the reason I did this was I noted the ball was slowly going vertical and then starting to pan into the other direction until it hit the corner of another brick.
Both are simple changes. I recommend trying them. Once I did this coupled with the shaped collider, the auto-play worked better.