Baja, Are you making any progress on this?
I think there may be some confusion based on the Shore Tie and Generator 120 Volts AC being "30-amp service" and the 30-amp auto fuse on the 12-volt-DC Converter/Charger unit.
Is your ONAN generator a MicroQuiet, 4KY series? If so, there's a circuit breaker ON the genny itself. Remove the access cover with its two latches. Facing you, there's the Start/Stop Switch. "Around the corner" to the right, lies the breaker, on the side of the panel with the Start/Stop on the Front.
To be ON, the Breaker Handle needs to be pulled toward you.
I'm gonna take a flyer here, and suggest that the Auto Transfer Switch/ATS did it job and threw the shore tie load to the genny. But the genny couldn't handle the surge and tripped that little breaker.
Problem with this logic, is the ATS should have flopped the load back over to the Shore Tie. Unless that was too much surge, too.
Something else I've learned. We have a 31-ft with 15000 Coleman A/C, an ONAN 4KY, and an ATS. Sounds like your setup. If the A/C is running, I can start the generator and it'll pick up the A/C "seamlessly." The A/C keeps running. But when I try plugging into shore tie with A/C running, then shutting the ONAN off, the transfer is ragged, and the A/C loses power for long enough that the compressor stalls on high head pressure.
Doing what I just said isn't a good idea, and I've stopped doing it. Our A/C doesn't have any compressor timeout built in, so I now shut it off before transferring either way, and wait about 10 minutes before re-starting it. Just wanted to point out that odd things happen on connect/disconnect to 30-amp 120 VAC power with heavy loads running.
Something's got your Converter/Charger (OB's third pic) offline. Your Step and Slide are no doubt hard wired right to your Coach (House) battery, and the other stuff you're missing is driven by the C/C unit.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB