Sol-Ark "Signal on" display

Over the weekend we had 100mph winds and most of the city is still without power. I estimate mine was out about 4 milliseconds but everyone else was given a 1-week estimate on the grid being restored.
This morning I noticed the LCD screen showing "Signal on" near the Grid icon, but our grid is still in shambles and I haven seen any documentation to explain the
notification. 15K version. Any clues?

I did stumble across this: https://diysolarforum.com/threads/sol-ark-12k-signal-on-message.37190/ which didnt show up in the search.
It appears the message is meaningless, or doesnt correspond to any recent action. First time ive seen it since my system went up.

I saw the same thing this morning, although our grid power is operating normally. I believe it appears (at least, one reason it can appear) is that the system is (at the time the message appears) allowing a generator to be connected, to charge the battery. My setting for the weekly generator exercise (although I don't have a generator connected!) is configured for a duration of 20 minutes, starting 8AM Monday morning, and that is when the "Signal On" appeared in the display! The "Signal On" indication then disappeared after 8:20 AM. So, I think that correlation says a lot.