Have you checked the position of the battery disconnect switch located just inside the door? I was parked in a campground last year and found that the batteries were not being charged.
Seems that the Intellitec disconnect switch must
be in the 'use' position for the converter to charge the batteries, even though you are plugged in.
OTOH, if you aren't getting any
12VDC into the trailer, it just might be the converter. To check it, disconnect the negative battery lead, plug in the trailer to 120VAC and put a volt meter across the 12VDC output terminals of the converter. You should see 13.5 VDC+. If not, the converter is not operaing to spec and should be replaced.