2013 Mazda Mazda3 pauses and jerks when shifting

[Al35]

I have a 2013 Mazda 3 with less than 60,000 miles on it. When I shift from park or reverse and the car has been sitting for a half hour or more there is a pause and then a jerk. It does not drive as if the transmission is going.The Mazda dealer put it on the computer and could not find the problem. I e-mailed Mazda and have not heard although they did acknowledge the message.