Rachio doesn't always run all zones sometimes not the entire time scheduled

Our Rachio Gen 3 has been working great for about 5 months. It has a drip schedule using 13 zones that runs every other night for a total time of 299 minutes, but suddenly lately we get messages that though it says it will run for 299 minutes, it returns a message that it ran less, sometimes only 158 minutes. We are stumped over what is causing this… anyone have any thoughts?