I have a dataset that essentially had a "dead spot" in the data points. It had values every few seconds for a few hours then nothing for 2 days and then started recording again. That dead spot shows as a single line as expected if zoomed only to that timespan but if you include either end then it is displayed not as a line but as the whole area shaded. I have attached a sample where I plot 1 - 10 in 1 second increments (making a stair step) and then plot a 5 at 900 seconds then an 8 at 990 seconds (I had to do this last point because the chart does not even display the last point in the series for some reason). From second 10 to second 900 the whole area between 9 ans 10 is filled. It seems like some sort of area average is calculated and filled once a certain amount of time has elapsed between points.

Is this a bug or have I done something wrong?