I could use some generator advice. I have a Onan in my class A and when I start it up as soon as it starts to send power to the unit it shuts itself down. So basically as soon as the transfer switch ...
Interesting that it would happen on the converter. The problem unfortunately can stem to a lot of things. What I would do is start pulling all 12V fuses out of the 12v panel to eliminate a possible short in anything. I'd unplug where I could, and disconnect where I could. Try to eliminate all going to the converter to see if that is blowing it.
Also, try ONLY turning on the main and converter breakers and see what happens.