Apparently, the power converter isn't charging the batteries, Ross! Either the converter is not getting the 110 volt AC power needed or the converter is malfunctioning.
Using an electrical multimeter, check the voltage to and from the power converter to discover if the voltage is sufficient on either end.
If the 12 volt lights work, check the voltage to the batteries to see if there is a broken or unplugged connection preventing the batteries from being charged.
You may need to get a wiring schematic for the converter from the dealer if you cannot isolate the problem. Good luck!