It may seem like killing the app was helping, but I'm pretty confident that's not the case. Rather, I'd be willing to bet that it's a case of cue ball bounces causing the problem and it's coincidence that the breaks following the ATK kills were those without loud bounces.
To prove this, the next time you run into this just hit the "Edit Results" button. From there you can adjust the automatic detection selections. It'll take a few tries to get used to how this works, but it's a fail-safe way of getting the speed from just about any break, even those with extra audio events (like ball bounces.) This is most prevalent with the BreakRAK or when using the alternate recognizer, but it's possible for very high bounces to also fool the normal recognizer.
As a side-note, if you're getting a high cue ball bounce (more than just a few inches) then beware that you're losing a lot of energy being delivered into the rack. There are two ways to fix this:
First, you can just adjust your cue ball position (move it back or forward a bit) so that the bounce position is adjusted such that the cue ball is hitting the table at the same place where the balls are racked. I'm personally not a fan of this, because this only works if you are consistent. It also means that you're not hitting the cue as level as you could/should be, and much of the energy is lost on impact when you are hitting the cue into the table.
The best solution is either (1) work to hit your cue as level as possible or (2) take a bit off your break to improve your accuracy.
Taking a bit off your break will actually allow you to deliver more power to the rack. If you try to break at 110% power (with 100% being your accuracy/power threshold), then you may be adding 10% into the cue ball but losing as much as 50% when the cue hits the rack. Net loss.
Find out what your 100% break is and slowly work to improve your accuracy as you add power.