I had some issues, yes. I leased a 2013 for 3 years, and it had an SSN that turned out to be wiring harness related (think this is a common cause). Apparently some of the contacts had slipped or were corroded or something, can't remember the details exactly, but it was fixed and then I didn't have any other major problems with that car. You might suggest to your son that he mention this possibility to the dealer. The difficulty with SSN is that it appears to be the car's response to a number of issues, and so the underlying cause can be pretty hard to determine...
I honestly can't remember for sure if it was that same car, or the 2016 I leased for 2 years, but I had another SSN that cleared itself up... I did some of the things people suggest trying when it happens (again can't remember exactly, yikes, but getting out and walking away with FOB or something), and the car started again and didn't require any repair (didn't happen again).
I did have a weird issue with the 2016 that I think the dealer misdiagnosed, to their own misfortune. Car was sounding funny... making a repetitive clacking noise, not super loud, but very noticeable. Dealer thought it was faulty bearings in the transmission; they couldn't acquire a new transmission, so the dude said they had to get the parts and rebuild it basically. When I got it back, it was better, but I could still detect a hint of that sound above 40mph or so... until I got the tires changed over for winter. Maybe the problem was just a tire balancing issue the whole time, and they rebuilt the transmission for no reason? Anyway, nothing else with that one.
For both the 2013 and 2016, all the repairs were taken care of under warranty. The 2018 has been a dream (knock on wood), other than the common plague of electric cars having disc brakes in wintery places like VT, where I live. Had to replace the rotors after only two years because they rusted out due to lack of use. I'm trying to regularly force friction brake use now (brake in neutral once/week or so, or slam on brakes type of thing), and we'll see how that goes. I think, assuming that transmission didn't actually need to be rebuilt, I'm about 2/3 as well. I have now bought the 2018, so I'll be able to report on its performance long term...
Hope some of this was helpful!
2018 FFE, Shadow Black, Leather
2016 FFE, Ingot Silver, Leather
2013 FFE, White Platinum