2020 Hyundai Sonata drivetrain & axles problems

Vehicle rough idled & eventually shuddered to a stop. This happened four times while in gear and idling at appx 1000-1500 miles. Between 1500-2000 miles, vehicle shut down while driving appx 60MPH on a county road. At appx 2700 miles, mpgs drastically impacted when vehicle suddenly stopped shifting gears properly while in motion at appx 70MPH on the highway. Check engine light appeared with message regarding ecs issues. Vehicle still drives, it just seems to struggle with efficiency and shifting correctly.

The contact owns a 2020 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the shift assists malfunction warning light illuminated. The contact turned the vehicle off and restarted the vehicle. The vehicle was towed to the dealer; however, the failure could not be duplicated. The vehicle was not repaired. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 21,000.