Reviving old thread here, but I'm experiencing something that sounds similar with my '18 Limited. At just under 15k miles currently.
For first several months of driving, shifting was super smooth. Has become much less so over time. Generally more noticeable shifts, but particularly when transmission skips gears...depending on acceleration, speed, going uphill/downhill, etc., the shifts can be occasionally be really hard and accompanied by really loud/harsh noise.
Had it in to the dealer recently. They said they did a reprogram, but tech also said he drove it and couldn't reproduce. My wife and I still notice the behavior and we'll have to take it back in and get someone to drive with us.
Anyone else come across this and have additional insight to resolving?