I called BMWUSA to let them know about the issue. They took down the information and said they'll "look into it". Doubtful.
For what it's worth, I registered a complaint with the NHTSA. If any of you are still experiencing this issue, I highly encourage you to do the same. An investigation/recall won't happen unless there are enough complaints. Here's the link to my complaint:
https://www.nhtsa.gov/vehicle/2019/B...FWD#complaints
I drove the vehicle for a few hours today in both open highway and city driving situations and the lag occurred every single time I tried to accelerate from a slow roll (auto-off was disengaged and I tested it in all three driving modes). I confirmed the engine doesn't rev during the lag. I also attempted to floor the accelerator during the lag (as another commenter suggested) and the vehicle did what I expected it would: after a few seconds, it exploded forward but with more force than before.
On a bright note, it looks great freshly washed.