I had a couple of outlets that were not working....heck, one was only working on the upper half, which told me that the outlets were NFG. When I replaced them, I was amazed at how cheap the quality was, but then figured that "Lowest Bidder" had come into play for the Mfgr.
Once I replace them, it's been fine.
But, I'd check the GFI first
You may also want to get one of those plug in Circuit Testers, they are pretty cheap, and good to have anyway, to test CG power....you may just have a lose wire?
Bill & Claudia / DD Jenn / DS Chris / GS MJ Dogs: Sophie, Abby, Brandy, Kahlie, Annie, Maggie, Tugger & Beau RIP: Cookie, Foxy & Gidget @ Rainbow Bridge.
2000 Winnebago "Minnie" 31C, Ford V-10
Purchased April 2008 FMCA# F407293 The Pets
The GFI is wired to control several other outlets which also go through your circuit breakers. I had same problem and rewired GFI which solved it. System is still protected with circuit breakers in the trailer and on the Rv site box.