Low Flow Detected alerts

Once a week or so I get low flow alert on one of my two zones, then a few days later I get low flow on other zone.
And some times on both zones on the save day.

Some say 0 flow and 1.2 expect.
But the zone watered ok.
One day I got 1.2 flow and 1.2 expected.

Any ideas on what to look at?
valves? city water pressure, software update?
Thanks I am getting tired of alerts.

I looked on line and it said this about previous week
18 gal
7 gal
20 gal
21 gal
22 gal
3 gal

and like i said, it looked like it watered ok. But from this i guess not

You most likely need to increase your pressurization time. Rachio takes a sample of the flow near the beginning of each run and then uses that for the flow rate for that run. If all the air is not out of the system completely until flow becomes uniform, that reading will be erratic and even 0 at times. Slight changes in pressure or your system can cause this to change over time.