I have the exact same car as your son that I bought in 2018.
Exact same thing happened to me when I first had it.
I had a Pontiac Fiero 4 speed manual shift which even when perfectly adjusted still required finess.
I had it 27 years. When shifting from first to second I would pull the shifter back and to the left.
This worked great.
When driving the Crossfire, old habits die hard even with automatic Crossfisre.
When shifting from park to drive I pulled the shifter to the left. It dropped into the "manual" mode and stayed in first gear waiting for me to tap right for an upshift.
Before any further inspection, I would suggest that when shifting from park to drive after initial start up, that he does not pull lever to left and confirms on instrument panel that the D is visible and not 1 (first gear}. If accidently if not confirming it is in D and it does stay in first gear, tap shift lever to right to upshift
Hope it is that simple.
Took me a few minutes of panic to realize what I had done when engine was revving and not shifting up.
Jim