Unlike the Rogue, when I go to around 50 MPH, regardless if I am going full throttle or driving economically, a whining noise comes, and its barely audible. The vehicle has roughly 3200 miles on it. I am thinking its a transmission issue, but I haven't had time to take it to the dealer to have it check, since they are on the other side of the county. Any clue on what could be making this noise?

Hopefully "Break-in" noise , of driveline in general. Keep a very close ear on it though ,ever trying to locate,
you know.

If CVT, whine is usually trans, may be normal or not. A certain very small amount likely is. Some cars simply have enough sound deadening on them to stop you hearing it inside the car. Cheaper ones no.

+1 for CVT whine

Most likely the CVT, yeah. By it's nature the CVT has a small whine sound to it. There's a few things that can also contribute to it as well.

-Check the transmission fluid level. If it's overfilled the fluid can be getting aerated which can cause additional whine or make it louder.
-Wrong fluid being used. Nissan usually recommends NS-2 or NS-3 (or equivalent) in their CVTs (check the manual, newer models tend to use NS-3), and it's what comes in them from the factory. Since it's a newer vehicle I'd doubt this to be a problem, but something to bear in mind whenever you change the fluid.
-Problem or wear issue with the CVT tensioner. Again, unlikely as it's a newer vehicle, but there can always be a defect.
-Check recall alerts/notices, or ask a (reliable) dealer if there's any known issues.
-Have a diagnostic ran at a dealer or mechanic with the appropriate equipment to see if the computer is picking up any problems or throwing error codes.

If your engine has a turbo they can whine as well, however the sound is usually louder/more pronounced and typically only kicks in during acceleration or under heavy load. I don't think the Kicks has a factory turbo version, though.

There's some other things that can cause a whine under the hood, but I'd start with these as they're the most common.

If it uses a rotary vane a/c compressor those will whine and normal. You usually hear that most at low speeds like under 30 mph.

Some serp belt runs make a whine too like Ford Focus which was known for it, normal.

Hearing a whine at 50 mph is not so much normal to me.

We have a 2018 Nissan Kicks SV and we are hearing the same noise that the dealer can’t hear. Ours happens at 70 mph while driving. Everyone said it’s road noise or normal.

Hi, I have a new 19 Kicks and I previously had a Versa Note. I believe that what you are hearing is the shift from low to high by the planetary gear that this particular CVT has. The Jatco CVT7WR and CVT7 works that way, perfectly normal and nothing to be concerned about. Youtube videos demonstrate how that works. If it's not that it could be the tires, mine has the Firestone FT140 and they are the worst tires I have ever seen.

Planetaries generally never make much noise if any, they are helical cut (specifically to stop whine) and then buried inside the outer drum ring gear and the sun is another front cover which muffles the sound; the whole thing is boxed up. Certainly not at higher speeds. When you hear a whine at constant speed and up higher at speeds say over 50 mph the sound almost has to be CVT chain as it is the only thing running at the speed and with the open construction (frees up sound to be heard) to make noise like that. The pulleys themselves being v-shaped focus the noise outward angularly like a megaphone.

Nobody mentioned a shift either, only constant steady state driving.

I'll agree with you if the sound is steady, then likely the chain. But aside from that the planetary gear does have it's unique sound when it's about to shift.