Stuck in reverse

I’ve had my 2019 XC40 (AWD, automatic) for approximately 2 months. I reversed out of a parking spot yesterday, and it wouldn’t shift out of reverse.
I pressed the parking break, but it didn’t work. I tried multiple times to get it to shift, but it didn’t respond until I unsnapped my seatbelt…maybe coincidental?
Has anyone else experienced this? Could I have safely turned off the engine with it still in gear?
It’s still under warranty, so I do plan to make an appointment. But until they can get me in, I’m wondering if there is any advice?