What does Health's "Show All Data do?

When I choose "Show All Data" from an activity in Health (iOS 8.1), I see a long list of data points with associated source app icons; but this list almost always seems to be incomplete and not to correspond to the data displayed in the dashboard.

For example when I choose "Walking + Running Distance", I see a bunch of data from "Phone", but none from recent days (the most recent entry is over a week old; today is Oct 21)

despite recent walks being recorded correctly in the dashboard ("Today" is Oct 21),

and despite the fact that those walks are from a different source (which I can confirm by choosing "Share Data" in the activity and selecting the source).

Is "Show All Data" not working properly? Is there a setting I need to adjust to get it to actually show all data?

it looks like Show All Data from the device is showing frequent short distance movements instead of the aggregated time and distance that Cyclemeter reports.

The Health app must be doing some kind of interpolation as well as merging or ignoring duplicates from the many data sets and points to generate the graph on the Dashboard.

also, checkout this answer.