"Your data in the Health app is encrypted with keys protected by your passcode, and never leaves your device unless you choose to back it up or grant access to a third-party app. When you do choose to back up your Health data through iCloud, it is encrypted both in transit and on our servers."
I noticed yesterday that the data was missing. But it reappeared later (though the dashboard was missing). When checking the data manually (getting to somewhere that has data, like Walking + Running distance) and trying to get all the data, it seems to try to load data, but doesn't get it (spinning wheel)
Given that the data was available later the same day, I'm guessing that the problem is related to services that are not as available as they should, probably due scale after all the devices using iOS 8.
This is all speculation, of course.
All data is stored on the device, there is no cloud component so this is unlikely.
Also, it seems to be losing whole days' worth of data from the MyFitnessPal app. For example, I'll have today's Nutrition data in there but tomorrow when I add breakfast it will likely have lost all today's data so the graphs always start "today" even though I had put data in yesterday. I'm not sure if this is HealthKit or the app, though, because things I put in manually using the Health app seem to stick.
https://news.ycombinator.com/newsguidelines.html
My dashboard only contains a few things I entered manually, and fortunately it's still there. I haven't been using a 3rd party app, yet. (iPhone 6 w/ 8.0.2)
