The inverter switch may be bad. Have you tried flipping the switch on at the inverter?
Our Onan display shows both the coach and chassis batteries levels, one screen for each. Perhaps you could post a picture of your Command Center displays, it sounds like they might be different from ours. But maybe some other '07 members can confirm.
We installed a Trik-L-Start charger in the coach battery bay connected to the chassis Aux Start relay which allows charging of the chassis batteries when on genset or shore power.
Typically the coach batteries are not connected to and charged while the engine is running.
Your converter/charger charges the coach batteries. It should be near the inverter.
You might consider joining the Seneca First Generation Owners group here;
https://www.jaycoowners.com/forums/g...on+owners.html