We recently purchased a 2021 Imagine 2800BH. Other than our walk thru we camped in the backyard to put everything through it’s paces before traveling hundreds of miles away from home. Power came by way of a converter to plug into 15A service since I haven’t gotten around to installing a 30/50A outlet. There was no need to run any major appliances. Propane ran heat/water heater and lights were all we used. All went well except one odd issue. I noticed that when I plugged my phone in to charge it in the USB ports it would sometimes charge and sometimes not. I tried using a standard charger plugged into an outlet and that also worked only intermittently. I thought maybe it was an issue with there not being enough power however, I experienced the same intermittent issue when camping recently with 30A service. Sometimes the outlet would charge a phone, sometimes it would not. I tested all outlets and they all behave the same way. What am I missing?