No battery power

I have a Heartland Fuel toyhauler and just recently noticed my batteries no longer supply power to it. I park it on the side of my house and leave it plugged in to shore power. I went out to run the generator and unplugged the shore power. Generator started up without issue. Everything working as should be, lights, water pump, and i ran the A/C for a while to exercise it.

Turn everything off, shut down the generator, and i no longer have any lights, or power at all. I go through everything i can think of. check batteries, they are good (they started the generator). Check all the fuses, even replaced them just to be sure. Plug shore power back in, all good, unplug shore power, nothing. I check the little breaker next to the battery thats bolted to the frame, getting power to both poles.

Im at a loss. What else is there to check?