Did you pull up wiring diagrams from the Winnebago site and pour over them? You might have had a wire-nut splice come loose somewhere. Winnie's diagrams will show every junction point. You can start looking for them and popping covers off to inspect the connections within.
Always the chance of a bad breaker, given the breaker is in the generator power feature, given the info you've provided so far. If your generator's like some I've seen, it has two outputs. One pretty much runs the coach as 30A and the second largely handles the second A/C...
2011 Winnebago Sightseer, correct? Please post the Model Number within that group that represents your coach. Maybe one of us will pull up a wiring diagram and look for possibilities.