If you have that sort of connection with and influence over DJI, I'll send you a list of software modifications I'd like to have implemented. I suspect others have things they'd like done, too.
There's your problem, the roof is steel and that's caused teh drone's compass to read improperly.
You've just been lucky in the past, but not this time.
The incident had nothing to do with the slope of the roof ... it was all about the magnetic...