One thing I noticed about my 2017 is that when I'm at a stop, with the foot on the brake and the drive mode set to auto, the transmission appears to shift into neutral. I don't know this for a fact, but I did notice that the car doesn't feel like it's trying to pull away. And in fact, when I take the foot off the brake it doesn't lurch forward at all for about a quarter of a second. So maybe the issue is going into neutral at a stop?
However, it might also do the same by applying the brake (possibly part of the hill launch assist feature). Hard to say. I'll try and watch the RPMs when I come to a stop, that should give me some insight as to what exactly it's doing in that case. At any rate, assuming that this is a possible explanation, are you by chance coming to a stop while on a hill, either uphill or downhill?