I'm not sure which breakers you may have checked but are you aware of the breaker directly on the generatorsat times?
They can be hidden down in the fiber "dust guard" and easy to miss if not checked there?
Have you found the online info from Winnebago here:
This is a snip of some of the 110AC portion. Click this to get a better view or go direct?
In on red or green from cord or genset and then transfer should send it out on blue!