Okay, thank you Phil for all the detail. I have identified the issue which was a miscalculation of the bounds of the graph. Before, the max was calculated as the start time + duration time. This never made sense because the duration is visualized vertically meaning there is no reason to extend out the max bound.
I have since fixed that in this commit: https://github.com/salbahra/Sprinklers/commit/157afd8f057aeaf54ea21b6405813c8a36d0d036. I will have this released in the next app update (~1 week).
This should fix all the graphical glitches you had showed me and allow unchecking of the “Rain Sensor” in the legend to rescale the graph and show the correct view.
In regard to deleting a specific day, I should have this functionality in there within the next update as well.