draining battery

Bought a lightly-used 2019 Thor Hurricane 29M from a dealer. Took one long-drive overnight trip, camped with no shore power and all 12V systems worked fine. Parked at home, connected to shore power briefly, and it was then unplugged for the last month. I went in and out a few times; step...

I have been having trouble recently with my house batteries draining or just not charging while plugged in to shore power. It is my understanding that when plugged in to shore power the batteries should always be charging or on standby and the power to the RV should all be from the power outlet...