I think you're breaking too far to the side to be hitting the head ball with full power. Either back off the power and settle for an even spread or hit the second ball with inside spin to get more action on the 8 and that also cause the CB to go to the rail and back into the spreading rack to get further secondary movement. That or just break more from the front and worry about spreading balls to run them, not making the 8on the snap.
For 8 ball, I place the CB on a line through the head ball to to the gap between the middle bottom ball and the ball next to it, and I aim for the back of the rack not front, trying to drive the CB and head ball through the back of the rack. I hit just hair below center on the CB and as long as I get good velocity, the CB usually hops and lands in the middle of the table. This looks like a barely off center break. It gives me the most consistent results by far. The 8 moves plenty but more importantly I get a full table spread so I don't care where the 8 goes, it's rarely tied up.
FWIW in a league match race to 5 tonight, I had three breaks with at least 3 balls down, and running it out every time with balls spread and none tied up. I also hit one 8 on the snap. My opponent got to shoot only twice, on the last rack, both times failing to escape safeties, which was good because in warm up I was not at all feeling it with my stroke, so those monster breaks saved me from actually having to play real pool.