Another piece of "evidence":
I have my own applet set up in IFTTT using the Rachio service and the Event Registered trigger. It's supposed to log a row to a google spreadsheet any time the Rain Sensor Activated event fires.
This applet has never run. (I set it up a couple of weeks ago.)
Today I observed an alert on the Rachio app on my phone at 2:46pm "Rain Sensor Activated." I waited til 3:30, and my spreadsheet still didn't have any new events logged. I went to IFTTT and ran the applet manually, and it immediately logged Rain Sensor Activated to my google sheet.
I don't have tools to diagnose this...