If you search the threads here you will find that a lot of people have had trouble with WFCO converters. Mine started acting up less than a year after a bought my TT new in 2012.
It took me 6 months to figure out what was happening. One of the first indications was the propane detector going off ... even when the valves were shut off at the tanks. Researching that problem mentioned low battery voltage being one of the things that caused that ... but for some reason I didn't make the connection. The problem progressed to nothing working even when plugged into shore power. (Oddly, to me, even the refrigerator would not work even when set for electric with shore power)
My TT battery finally died completely and I had to replace it. Less than a month later it was drained even thought the TT had been plugged into shore power the whole time. That's what finally got my attention and made me check the converter. Turned that the AC side was working fine but the DC side was putting out about .10V. That's one tenth of a volt.
I replaced it with a Progressive Dynamics drop-in replacement from bestconverter.com ( PD4655 55 Amp Converter Upgrade Section
) and I have not had a problem since. Not with battery or propane detector or refrigerator or anything. Only took about an hour to make the swap. Perfect fit.
I suggest you just bite the bullet and replace your converter. IMO, WFCO is junk, plain and simple.