Sorry I know this thread is a little dated. I am new to this forum and stumbled upon this thread and would like to add some hopefully "helpful to someone" input. You at one point said "I may well be the only one...". You are not.... I run probably about 800 Generac Air cooled service calls per year (that's a modest number). Just due to sheer volume, an issue that someone else has seen once or twice I have probably seen 50+. This problem is actually more common than you would think.
Issues I have seen with these Advanced Monitors: (I will start with yours)
The time and date, as well as the exercise time, are settable from the remote control. However, the remote control often does not sync accurately to the generator controller. Therefor, you may think you are setting the correct time and date. However, if you check the clock on the generator it may be potentially off by hours, days, months, even years. This can occur while trying to set both the actual time, as well as the exercise.
Most commonly: I see controller exercise times set for 1-2 minutes prior to its intended set time. EX: 9:58 as opposed to 10:00. This particular issue is usually not a big deal, and goes mostly unnoticed.
As a sort of continuation to #1.... You may be saying, "well I never tried to adjust the time or date from the remote"... It doesn't matter.... Sometimes the remote controls will just arbitrarily decide to start messing with the clocks on their own for absolutely no apparent reason. Unfortunately I do not have a video of this, but i have actually stood at a generator and watched its clock change to a completely different time, date, and year about every 5-10 seconds for as long as I watched it. As soon as I switched the remote control off, the problem instantly stopped.
^^^ this is most likely what you are experiencing. The genset ran as intended at its normal time. But then at some point later, the remote changed either the actual time, or the exercise time. As far as the generator was concerned, it was running at "2PM on a Wednesday" when it was ACTUALLY 4AM on a Saturday. I have had multiple instances where customers have told me their generator has run 3+ exercises in a matter of a single week. Never at the same time of day.
This next issue, while I have seen this probably 100 times, I really do not have an explanation for.... They say pictures are worth 1,000 words, so I am going to let this picture do the talking (link below)........ take note of the time and date in the photo. ?!?!?!?...... My boss told me he would give me a raise on the second Wednesday of next week, I figure it's about time he pay up..
Again, I do not have a video. But yes, the clock will actually count up to this time like it's no big deal.... and while this picture does not show it, there are apparently also 72 seconds in a minute. This particular issue usually occurs along with the rapid time changes stated in issue #2. The generator controller is smart enough to know those times don't actually exist. But none the less the remote is telling it to change time, so it's trying as best as it can to comply.
Finally the infamous "radio signal loss". These things run off the same frequency as routers, baby monitors, portable house phones, and of course microwaves.
They can not maintain a connection to save their lives.... And the problem is that once a connection is lost, it can be difficult to reestablish, usually requiring going to the generator, and unplugging the transmitter from the control board in order to reset it.
Honestly, your best line of defense from these scenarios is to make sure that the AAA batteries inside are fresh. Even, if you leave the device plugged into an outlet. I most commonly saw these problems once the batteries started to become weak. And second, never ever ever, change the time or date from the remote control. Always, make those adjustments at the generator controller.
Again, sorry about bringing up a old thread. As well as its lengthy nature. But again, my findings are based on collectively probably 100 occurrences. Not just a 2 or 3.