Can you identify the ground and neutral wires from the gen? The other 2 wires are the hot wires and you should have 120V to both hot wires from either ground or neutral. You must measure from the gen wires as the neutral and 2 hots are switched in the ATS.
Wire colors aren't reliable as mfgs can use whatever color they want. But it would be nice if the ground was green and neutral white.
OK If you don't have 12V to the panel and elsewhere then that needs to be resolved. A lot of RV equipment depends upon 12V. Perhaps that's your refer problem.