FURNACE NOT LISTED ON THERMOSTAT

At the very lleast I’d have gone up on top the RV and removed both Zkne 1 and Zone 2 covers and reseated the RJ11 CANBUS cable. And while I was there I’d verify two blue wires for Zone that is not seeing furnace

If the electronic control module has failed or CANBUS integrity is compromised then the control module for that furnace will not “see” the furnace...

Replacing the furnace control module will most likely accomplish nothing.