DJI's stance on the "myth"
From DJI support:
"When flying a DJI drone over water, the sensors can experience issues due to the reflection of light on the water surface, often causing the drone to become unstable or erratically adjust altitude...
I've always done my imu calibration on my dining room table, never had a failure yet. Probably done dozen times in my life of many drones. Only ever needed when flights got squirrelly. Good luck
I once saw a cartoon in Calvin and Hobbes where Calvin said that "the fact that aliens haven't contacted us yet proves there is intelligent life in the universe."
Yours was far more extreme than mine. I just found it odd that there is a certain shopping complex that in a very certain area, even at altitude my drone loses GPS. : ) I don't believe it really lost everything because it did not even go into...
Yes - that's been my experience over the time I've been flying, but I was looking for some way to explain the "collision" warning that popped up for a second.