Looking at the graph details the calculations look like you bottomed out today, even after watering yesterday.
I don't see any software defects. If your reservoir was bigger than it wouldn't have watered today.
Am I missing something?
Your saving grace last week was all the precipitation, or you would have watered very frequently.
Also FWIW, your irrigation amount looks really small (.30 inches). Looked at your AWC which is .1 inches, which seems shallow. It doesn't take much ET to pull that down to zero. In CO that is only about 1.5 days.
For comparison my irrigation amount is .48 inches with a AWC of .16 inches.