I see Null on mine as well, I pulled a VIN from a Big Bend (Similar Spec as mine) that is sitting built at my dealership and its also null there. Besides that, my build matches the Big Bend at the dealership. So might not be an issue to have that as "null".
Mods Popped for me tonight! 1/20/2022 blend, 0913 rotation, 1316/1542. The tracker seems down for me so no idea on estimated ship date, but hey, I'm happy! Shes alive!