The contact owns a 2018 Jeep Grand Cherokee. The contact stated that after stopping the vehicle and shifting into park(P), the vehicle started rolling backwards in the driveway. The contact stated no warning light was illuminated. The contact stated that the failure had occurred several times. The contact had taken the vehicle to a local dealer who was unable to duplicate the failure. The dealer advised the contact to use the parking brake while parking the vehicle. The vehicle was not repaired. The manufacturer was not informed of the failure. The contact had researched online and related the failure to NHTSA Campaign Number: 24V838000 (Service Brakes, Hydraulic); however, the VIN was not included. The failure mileage was approximately 76,000.