Do you look at the right place to find Batt2 voltage?
In the HUD, I have my Power module battery voltage (11.57)
In the Quick screen, I choose Batt2 Voltage (double click to select display item).
Value displayed is 5.00v, it change slightly when switching on led lighting.
My voltage multiplier is quick and dirty guess. I did not check the real bec servo rail voltage with multimeter before.