First off....
Converter has nothing to do with RV having 120V AC power
It is fed 120V AC power via an individual branch circuit breaker and converts that AC power to DC power (to recharge battery and supply the 12V DC System when AC power is available)
120V AC power comes from your shore power cord OR Generator
Each AC source goes to the auto transfer switch which then passes the 120V AC power to your MAIN AC Power Panel (where rv main breakers and the individual breakers are)
Most transfer switches default to generator side. Gen ON then transfer switch swaps to gen side so it supplies the AC power
THen when gen is off and shore power is connected it swaps back so shore power supplies the AC power
Sounds like the transfer switch relays/contacts stuck/burnt on Gen Side and not swapping to shore power side.
Look for a metal box with shore power cord, gen power cord going in and then main cord coming out.
That is the ATS (auto transfer switch)
If you are NOT comfortable/understand working on 120V AC then most you can do is whack the box with shore power on and see it it swaps.
Otherwise lid has to come off, connections checked, relays/contacts inspected
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31