Your toyhauler is set up to have 50 Amp service, so the input to it is 240 volts two phase. That means that each side of your breaker panel is getting 120 volts, but loads are on both sides of the panel.
When you feed it with a 30 amp RV plug that plug is 30 Amps, but only single phase. This kind of feed only feeds one side of a 240 volt panel.
In a nutshell, you are only feeding one side of your main breaker panel. All the devices that are not working are fed from the other side of your main breaker panel.
Go to your main breaker panel, and verify that the things working are on one side, and the things not working are on the other side.
A competent electrician could set up your system so you can get power to all your devices, but it must be carefully checked and also removed before you plug into anywhere else.
