When I first go into a site I check the campground service. First I check for polarity with a polaritymeter. It is made for 15Amp, 110V house outlets but works fine in the adapter for 30Amp service as shown.
I also have a Volt-A-Chek meter to make sure some goofus didn't wire 220 into a 110 outlet. It can be used in the same 30Amp adapter. When not in use I do leave it plugged into a outlet so I can monitor power levels for times when the fridge isn't cooling like I want or the A/C isn't cooling properly.
Many times the camper problem comes from outside sources. Once I've checked my incoming services and they are operating at proper levels I will then move onto my own equipment. Especially when things werk at home but fail when away from home.
YOu didn't say if things were werking properly once you returned home.
I hope your problem was low campground current or something similar.