It looks to me more like "today's" watering is not subtracted. I have zones that watered today. One, a pot drip system, was way over saturation. I "emptied" it and the graph went to empty for yesterday and jumped back to saturated on "today's" watering even though I emptied it after it had watered. I emptied it multiple times. I guess that is what you said, but how do I "zero" out things in this case?
I guess I have to figure out why it thinks it watered enough to make it saturated again. I know from observing the plants that the watering is about right, any advice on "configuring" pots on a drip system?