In these situations, it might not be a bad idea to also do a quick check of your RV connection to the power. Check to see if the power cable and especially plugs/sockets along it are more than a little bit warm (indicating a localized voltage drop, typically caused by a poor connection or physical damage of some sort).
If you are having a drop of a few volts in the lead cable under load, both the EMS and the tech's meter could be telling the truth simultaneously, and you may have a fire hazard as well.