The regulations matter, not what your tablet is showing. That's like ignoring the "No Truck Allowed" sign because your GPS says turn left onto that street. You should NOT use the split break until you understand it backwards and forwards. It's extremely easy to make a mistake and then have an "egregious HOS violation." Think about getting caught driving 6-10 hours after being 15 minutes short on a sleeper break. All of those driving hours then become in violation because of a 15 minute error. As soon as you stop, when using split break, go in the sleeper. Note how much of your 14 hours are still available, and write it down. 8 hours later you still have those work/drive hours available.
Someone on here has put up a detailed explanation of the 8 hr. split. I can't tell you any more. I use the BigRoad app to figure out how I can put an eight hour break to good use. I put my anticipated hours and the 8 hr. break into the app and see how it pans out. I run on paper and use the app to stay legal while using the 8/2 split.