I'm sporadically experiencing this problem with my 2012 G37 sedan, 7AT, where I apply gas, the engine revs but the car does not accelerate - like the transmission is slipping. No sounds aside from the engine. It happens only when the car is already moving at relatively low speeds and under gentle acceleration. I've only ever noticed it happen when I'm going up or down a slope, like the ramps in a parking garage.
Typically, I'd think low transmission fluid but I've no reason to think that's the case as there's no indication of a leak or damage. Wanted to get some other opinions.