I have experienced a few times loose connections that make things like AC not work right. My first house had the AC go down one day. Found loose connections at the circuit breaker box and just a quick turn of the screwdriver fixed the problem. Just recently I purchased a 2014 Winnebago Journey with 50amp service. The AC sometimes worked and sometimes did not when on shore power. A quick shutoff to the power and back on fixed the problem. Never had a issue with the genny. After this happened 3 different times I opened up the transfer switch box and put the screw driver on all the terminals. The power cord terminals were snug, but not tight. After I tighten them down problem solved.
You could be seeing something similar either in your pedestals or the customers RV. If you decide to check for loose connections please have someone that knows something about electricity do this for you as you could get shocked if not done properly.
