Weird electric problem

[John from Central Florida]

Can't say I've experienced this before...
Started up my inverter generator this morning (on full power) for a few hours to recharge my twin 12 volt deep cycles.
After about two hours I went to check the voltmeter I have wired into my battery bank. No charging was indicated. Checked some inside 120 volt sockets and all were dead. Breakers in the WFCO were good (not triggered, solidly engaged). I did not mess with them at this point. The GFI had not triggered, either.
All 12 volt appliances were working fine.
So, I hooked up my Progressive EMS between the generator and trailer line, and no errors were indicated.
All the manuals were useless, of course.
Back in the trailer I switched off all the breakers, and pushed the 12 volt reset button. Now, everything is running fine, all sockets have power, and the batteries are charging.
Strange...