Before I realized that the plot is actually "scrollable" and the all the expected data is actually there.
For me, it looked like Hard Disk Sentinel is misbehaving and just lost all the temperature history. And the "Health (%)" history on the "Overview" tab.
Meanwhile, the individual S.M.A.R.T. attributes history looked normal - the whole history is visible, as expected.
On the other my PC, this plot contains about 14 points, so it does not look that weird.
I guess, the idea is to show the past two weeks. This might make sense, but for me this was confusing.
I'd suggest to:
- show the whole history for Temperature and "Health (%)" plots, just like for S.M.A.R.T. attributes
- add zoom ("Select dates range" in the context menu, maybe?)
- plot line towards the previous point, even if the previous point itself is not visible