Initial searches haven't turned up anything, so hopefully someone has seen this before.
On this DH I'm working on, if you choose ramp skill shot, the ball will bounce up into the opto bracket for the right loop, most of the time, it will bounce back down the loop and the magnet won't catch it. You can see it's been doing this a long time.
I took some slow motion video and it seems when it's launched clean through the "jump" entrance into the loop, it's going fast enough that it bounces higher into the bracket and rebounds back. Sometimes, it'll hit the plastic above the entrance, which slows it down enough that the magnet can grab the ball before it rolls back down the loop.