[C&P RV]

Have you tried:
1) turn off the inverter in the battery bay with the large red rotating switch
2) disconnect from shore power
3) verify the inverter controls in your photo are completely dark (off)
4) turn inverter back on at the rotary switch - so it's only powered by the battery
5) power on the inverter at the inverter control and attempt to switch the setting - page 26 of the inverter manual.