sounds like (house) batteries are low to me....especially when you consider you were able to start the generator w/ the coach running (most coach engine/alternators charge the house batteries when the coach is engine running)
Id put a voltmeter on the (house) batteries w/ everything turned off & see what the charge level is, my bet is you're gonna show low voltage.
couple of choice if the (house) batteries are low (v) - run the generator (to charge the batteries), connect to shore power so the converter/charger can charge the batteries or drive/run the coach so the engine alternator can charge the (house) batteries.
if the coach has been connected to shore power then i don't know why the battery voltage would be low - unless you've been cranking not he generator starter a bunch or your converter charger is not charging the (house) batteries.