Where are you looking at the breakers (pedestal or internal panel)?
- If the pedestal, you should be plugging into the 30amp outlet. A 20amp might work but it's marginal. It's not separate for the microwave.
- If it's the internal breaker panel (inside the RV), the 30amp should be the main breaker that kills power to all the other breakers. They often don't do a good job of labeling.
Are you trying to run the microwave at the same time as the air/con? If yes, there's your likely problem.
Easy way to check if it's the microwave breaker is to flip it off. If the clock on the microwave goes off you found the microwave breaker.
What is the voltage arriving at the RV? It's relatively common for park voltage to sag during peak demand on hot summer weekends. As voltage goes down, amperage goes up to compensate. Especially if the aircon breaker is getting weak, this could be enough to pop it. (The generator is only servicing your RV, so voltage should hold up fairly well).
