Hmmm - I didn't even realize there was a standby more that could be turned on or off. I've seen that in the control panel, but just thought it was automatically in standby mode whenever it wasn't actively running a zone.
I do have Alexa integration and my wife has been using it frequently to water some new plants. When she does this, she just runs a specific zone for 10 minutes. I didn't realize that would impact any schedules, other than knowing that those specific zones had gotten some water so if they are part of a flex schedule might skip their next cycle or whatever to compensate.
I turned off Standby mode and things look normal now, where i see the calendar and zones showing next watering days as expected.
I didn't explicitly turn on standby mode, so I'm curious what triggers it. I recently had a new zone installed for the pool, and the tech used the manual buttons on the controller to test it, could that do it? You mentioned Alexa can cause that, but I would only expect that if someone gave the specific command through Alexa to put it into standby mode.