Take a few more battery voltage readings.
1. Not plugged into shore power but sun shining so solar providing power
2. Not plugged into shore power but at night with no solar power
3. Plugged into shore power at night with no solar
I'm thinking battery or converter, or both. A bad battery doesn't explain why things don't work on shore power, unless the battery has a few shorted cells, but then I doubt things would work for you when the solar is generating.
I did notice the circuit breaker "GFCI-FRIG" appears to be off. That would limit your fridge from working on AC when on shore power but it should still work on 12v provided the battery voltage is there.
Does your camper have an inverter to generate AC while on batteries? If so there may be a transfer switch/relay off or malfunctioning.
