Why the discrepancy in heart rate graphs?

[aubergine]

I am trying to understand two anomalies in the way that Fitbit reports and graphs heart rate data on the app.  

1.  Two heart rate graphs in the app are never completely consistent with each other.  If I select the heart rate icon from the main screen and then select "Today" from "This Week," I get a graph like the first one below (Graph 1).  If I then click on the double arrows, a larger version pops up (Graph 2).  However, the larger version always displays a different heart rate range.  It is not just the case that the range looks different because the second graph is larger and uses a vertical-axis different scale.

In case you can't see what I am talking about, the first graph shows the rate ranging from a high of approximately 68 to a low of approximately 55.  For the second graph, the range looks like it has a range of 65 to 58.  The second graph always shows a narrower range.  It also (later in the day, after I have been out and about) may show little to no cardio, even though the first graph reports minutes of cardio.  This is clear because of the color coding.  Graph 1 will show orange areas while graph 2 is solidly yellow.

2.  If, later in the day, I look at the larger graph, the range will change.  Here is what it looks like later in the day.  Note that the early morning hours now show that my heart rate only briefly dipped below 63.3.  This is not what the same graph showed earlier in the day.

I can't see why these inconsistencies arise.  Either my heart rate got below 60 for part of the night or it didn't.  Either I had "x" minutes of cardio or I didn't.  And I can't see how it could be reported as "below 62 for most of the night" and later updated to "above 63" for most of the exact same time period.  I'm not taking the heart rate measure all that seriously, but I would like to know what the updates mean.

[LZeeW]

@aubergine   There is a known issue with the heart rate display on the iOS app.  The engineers are aware of it.

The y-axis numbers are off in the expanded view.  If you lightly press and hold on the graph, you see the correct number.

[Nothanks59]

This issue has been reported for several months. The reply from mods has pretty much been a constant “we are aware. We don’t have a timeline for a fix.” Honestly it doesn’t seem to be a priority for them. I have lost faith in our ability to point out bugs and get a substantive response.