I actually have observed this on two occasions. Now, when I look at the historical record at pwsweather.com, I see that there are differences in the two occurrences. In both cases, the PWS in question was PAULCROSS4.
If you look at the monthly report for November 2016, you'll see that there is a big gap during November 24 - 30 when no data was reported. Somewhere during that time, I noticed that my controller's watering schedule ran inappropriately.
More recently, on February 23, I noticed that my controller ran even though there had been heavy rainfall in the preceding several days. When I looked at pwsweather.com at that time, I observed that the PWS had not reported any data for several days. But when I look now, I see that there is no gap in the data and that the heavy rainfall was correctly reported. Apparently, the data for those days wasn't lost, but was hugely delayed (by several days) before being reported to pwsweather.com.
In both cases, the data wasn't available to Rachio when it was needed; hence, my feature request for a backup weather station to use if a station hasn't reported for more than a few hours.
(The PWS in question is not mine; I do not know anything about it except that it is located near me. Since the February occurrence, I have reverted to using the nearest NWS station, KNUQ.)