Stopping on a steep incline with a golf cart; being electrically run, you have removed all of your forward kinetic energy and the 48 volt system, its motor and gears do not have the required torque and wattage to move that amount of mass into forward motion once again on the incline. The ‘click’ you hear is the relay releasing the drive mechanism from the electrical power. Hence, you coast back down to the starting position. Best solution, don’t stop.
Golf carts weren't designed to go up steep inclines; just a leisurely cruise around the golf course. You could of course modify the gears and up the wattage to make it do what you are asking but that could be expensive.