If your ceiling lights/fan (all 12v) work when you are plugged into shore power, it's possible that your coach battery switch was set to disconnect the batteries, that would explain the power 120 to coach converter to 12v lights/fan etc.
If the disconnect switch position doesn't change the other 12v issues, look for additional fuse panels and a large r fuse or 12v circuit breaker that protects them.
On our c-class there are 2 12v panels, different locations, for the house portion and another 3 for the Ford chassis.
Ken