DJI have obstacle sensors in the front, back, sides, top and bottom. they are designed to keep you from running into things. But they cannot see everything. One of the sensors is miss aligned or faulty. Fairly reasonable fix for a DIY. Or it can be sent in. But this error has not effected use.
One other thing. I really want to purchase the DJI Mavic 2 Pro. Thanks again and E SAFE!