I seem to remember that the panel voltage needs to exceed the battery voltage before the solar charge controller will begin to deliver charge to the batteries.
Also, once the batteries are fully charged, the solar charge controller will stop delivering charge to the batteries until the the battery voltage drops to a certain point. I do not remember this voltage.
If the batteries are fully charged, and the solar panels are under sunlight, placing a load on the batteries should cause the charge controller to send charge to the batteries.
I would place the trailer in the sun, turn on a load, maybe the inverter, and see what happens when you do. Make sure you are using the Victron phone app connected to the charge controller to monitor amps delivered to the batteries.
Hope this helps, we absolutely love our LE2.