Paul127,
What I would expect is that power from your CB panel goes to the 2012 and then on the rig plugs. The transfer switch inside the unit switches between the incoming power and the inverter. This would be the basic wiring.
Having 120V at the panel does not mean that you have 120V at the 2012. Do you have 120V into the unit and 120V out of the unit on shore power?
Do you have a 30A CB in your panel for the unit? Since you don't have CB's in the unit I would expect to find them elsewhere. The suggestion to check GFCIs is a good one but that is not a CB. What else can you find?
