Welcome Curt & Susan to the Newmar family.
Congrats on your new Grand Star many safe travels.
The charging system is controlled by the BIRD System.
If your coach is plugged into a 110 outlet the house batteries will be charged and when they are fully charged than the chassis battery will be charged.
The alternator will work in the opposite direction charging chassis battery than house batteries.
My Gen starts from the house batteries they may have changed your model coach you can disconnect the house battery ground and see if Gen starts.
The 12" square solar panel keeps the chassis battery charged for parasitic loads LP Detector,ecm,tcm,steps, radio.
When coach in storage I have a LP Detector switch in display tank level area to shut off as not to drain chassis battery which it feeds off.