Yes, it often happens when you shift into reverse too quickly after starting the engine. The monitor or computer does not seem to have started properly and gets confused when the reverse gear is engaged.
Infiniti seems to have really cheap components installed there or the performance of the CPU is simply too weak.
Jumo is correct. It happens when you shift into reverse too quickly after starting the engine. I recently traded in my Q50 which had the same software and it had the same issues. Sometimes the screen will go blank and sometimes even after you put the car in drive you'll see that the reverse camera is still on. I thought it was just my particular Q50 that had those issues but they followed me to the QX30.
20-30 seconds? Obviously, something is not working and this would be more than simple to show the dealer
As also mentioned above, I was assuming you were pushing it to R right after you pushed the start button...I have done that when I was in a hurry, but then I push P and push it back to R and all is good in the world.
It's a known issue with the system and there is no fix. Letting your car idle for 20-30 seconds isn't necessarily a bad thing unless you're in a hurry. The motor and oil will warm, and the coolant will flow.
It does happen to my sometimes, but I never have to wait 20-30 seconds to put it in reverse. I put it in reverse probably 1 second after starting the car, and most of the time it works, but occasionally, it is black.