Recreational Vehicle Lpg Tank Valve/gauge problems of the 2016 Hyundai Tucson

While stopped, with car in drive, pressing accelerator engine revs (4 to 5 on the gauge) but does not go forward. Car then jerks forward and then finally moves. I sat thru 3 red lights before the car actually moved. This occurs on city street this occurred once before but the forward motion "caught" quicker than the last time at the same time this occurred the ac failed as did the bluetooth. The phone said it was connected but the car said it was not . The ac fan worked but blew hot air. The ac and phone worked after turning off car at dealership. The tech at dealership captured on video the gear clearly in drive and the car was rolling backward. Service center said no error codes were recorded. Hyundai USA has no information to give me. Car has been at dealer service dept for 11 days now. Concern is safety of vehicle to myself and others with the sudden acceleration and car going in reverse while in drive.