I'm facing with a similar sitiuation which frustrates me as hell - in a health app. I've bought iP 6s Plus and for someone it may be difficult to understand but I use health app to monitor all my activities, calories etc., so that's why this is my crucial app, which I visit several times a day. On iPhone 6s plus however this application crashes everyday at least once - display remains white and shortly after that app crashes by kicking me back to the springboard. Unfortunately I can only make a hard reset of the device. I am so pis... angry about that :/